diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8305443a19bac..982a66ef58720 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -12519,7 +12519,7 @@ namespace ts {
                     source = getSimplifiedType(source, /*writing*/ false);
                 }
                 if (target.flags & TypeFlags.Simplifiable) {
-                    target = getSimplifiedType(target, /*writing*/ true);
+                    target = getSimplifiedType(target, (source.flags & TypeFlags.IndexedAccess) !== 0 && (target.flags & TypeFlags.IndexedAccess) !== 0);
                 }
 
                 // Try to see if we're relating something like `Foo` -> `Bar | null | undefined`.
diff --git a/tests/baselines/reference/complicatedIndexedAccessKeyofReliesOnKeyofNeverUpperBound.errors.txt b/tests/baselines/reference/complicatedIndexedAccessKeyofReliesOnKeyofNeverUpperBound.errors.txt
index af63c18523d6a..ceee293b747d9 100644
--- a/tests/baselines/reference/complicatedIndexedAccessKeyofReliesOnKeyofNeverUpperBound.errors.txt
+++ b/tests/baselines/reference/complicatedIndexedAccessKeyofReliesOnKeyofNeverUpperBound.errors.txt
@@ -1,24 +1,21 @@
 tests/cases/compiler/complicatedIndexedAccessKeyofReliesOnKeyofNeverUpperBound.ts(33,5): error TS2322: Type '{ type: T; localChannelId: string; }' is not assignable to type 'NewChannel<ChannelOfType<T, TextChannel> | ChannelOfType<T, EmailChannel>>'.
   Type '{ type: T; localChannelId: string; }' is not assignable to type 'Pick<ChannelOfType<T, TextChannel> | ChannelOfType<T, EmailChannel>, "type">'.
     Types of property 'type' are incompatible.
-      Type 'T' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] & ChannelOfType<T, EmailChannel>["type"]'.
-        Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] & ChannelOfType<T, EmailChannel>["type"]'.
-          Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] & ChannelOfType<T, EmailChannel>["type"]'.
-            Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-              Type 'T' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-                Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-                  Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-                    Type '"text"' is not assignable to type 'T & "text"'.
-                      Type '"text"' is not assignable to type 'T'.
-                        '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
-                          Type 'T' is not assignable to type 'T & "text"'.
-                            Type '"text" | "email"' is not assignable to type 'T & "text"'.
-                              Type '"text"' is not assignable to type 'T & "text"'.
-                                Type '"text"' is not assignable to type 'T'.
-                                  '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
-                                    Type 'T' is not assignable to type '"text"'.
-                                      Type '"text" | "email"' is not assignable to type '"text"'.
-                                        Type '"email"' is not assignable to type '"text"'.
+      Type 'T' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] | ChannelOfType<T, EmailChannel>["type"]'.
+        Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] | ChannelOfType<T, EmailChannel>["type"]'.
+          Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] | ChannelOfType<T, EmailChannel>["type"]'.
+            Type 'T' is not assignable to type 'ChannelOfType<T, EmailChannel>["type"]'.
+              Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, EmailChannel>["type"]'.
+                Type '"text"' is not assignable to type 'ChannelOfType<T, EmailChannel>["type"]'.
+                  Type '"text"' is not assignable to type 'T & "email"'.
+                    Type '"text"' is not assignable to type 'T'.
+                      '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
+                        Type 'T' is not assignable to type 'T & "email"'.
+                          Type '"text" | "email"' is not assignable to type 'T & "email"'.
+                            Type '"text"' is not assignable to type 'T & "email"'.
+                              Type '"text"' is not assignable to type 'T'.
+                                '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
+                                  Type 'T' is not assignable to type '"email"'.
 
 
 ==== tests/cases/compiler/complicatedIndexedAccessKeyofReliesOnKeyofNeverUpperBound.ts (1 errors) ====
@@ -59,24 +56,21 @@ tests/cases/compiler/complicatedIndexedAccessKeyofReliesOnKeyofNeverUpperBound.t
 !!! error TS2322: Type '{ type: T; localChannelId: string; }' is not assignable to type 'NewChannel<ChannelOfType<T, TextChannel> | ChannelOfType<T, EmailChannel>>'.
 !!! error TS2322:   Type '{ type: T; localChannelId: string; }' is not assignable to type 'Pick<ChannelOfType<T, TextChannel> | ChannelOfType<T, EmailChannel>, "type">'.
 !!! error TS2322:     Types of property 'type' are incompatible.
-!!! error TS2322:       Type 'T' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] & ChannelOfType<T, EmailChannel>["type"]'.
-!!! error TS2322:         Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] & ChannelOfType<T, EmailChannel>["type"]'.
-!!! error TS2322:           Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] & ChannelOfType<T, EmailChannel>["type"]'.
-!!! error TS2322:             Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-!!! error TS2322:               Type 'T' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-!!! error TS2322:                 Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-!!! error TS2322:                   Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"]'.
-!!! error TS2322:                     Type '"text"' is not assignable to type 'T & "text"'.
-!!! error TS2322:                       Type '"text"' is not assignable to type 'T'.
-!!! error TS2322:                         '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
-!!! error TS2322:                           Type 'T' is not assignable to type 'T & "text"'.
-!!! error TS2322:                             Type '"text" | "email"' is not assignable to type 'T & "text"'.
-!!! error TS2322:                               Type '"text"' is not assignable to type 'T & "text"'.
-!!! error TS2322:                                 Type '"text"' is not assignable to type 'T'.
-!!! error TS2322:                                   '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
-!!! error TS2322:                                     Type 'T' is not assignable to type '"text"'.
-!!! error TS2322:                                       Type '"text" | "email"' is not assignable to type '"text"'.
-!!! error TS2322:                                         Type '"email"' is not assignable to type '"text"'.
+!!! error TS2322:       Type 'T' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] | ChannelOfType<T, EmailChannel>["type"]'.
+!!! error TS2322:         Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] | ChannelOfType<T, EmailChannel>["type"]'.
+!!! error TS2322:           Type '"text"' is not assignable to type 'ChannelOfType<T, TextChannel>["type"] | ChannelOfType<T, EmailChannel>["type"]'.
+!!! error TS2322:             Type 'T' is not assignable to type 'ChannelOfType<T, EmailChannel>["type"]'.
+!!! error TS2322:               Type '"text" | "email"' is not assignable to type 'ChannelOfType<T, EmailChannel>["type"]'.
+!!! error TS2322:                 Type '"text"' is not assignable to type 'ChannelOfType<T, EmailChannel>["type"]'.
+!!! error TS2322:                   Type '"text"' is not assignable to type 'T & "email"'.
+!!! error TS2322:                     Type '"text"' is not assignable to type 'T'.
+!!! error TS2322:                       '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
+!!! error TS2322:                         Type 'T' is not assignable to type 'T & "email"'.
+!!! error TS2322:                           Type '"text" | "email"' is not assignable to type 'T & "email"'.
+!!! error TS2322:                             Type '"text"' is not assignable to type 'T & "email"'.
+!!! error TS2322:                               Type '"text"' is not assignable to type 'T'.
+!!! error TS2322:                                 '"text"' is assignable to the constraint of type 'T', but 'T' could be instantiated with a different subtype of constraint '"text" | "email"'.
+!!! error TS2322:                                   Type 'T' is not assignable to type '"email"'.
     }
     
     const newTextChannel = makeNewChannel('text');
diff --git a/tests/baselines/reference/indexedAccessRelation.errors.txt b/tests/baselines/reference/indexedAccessRelation.errors.txt
index 84e65df856d28..fe2843a662e51 100644
--- a/tests/baselines/reference/indexedAccessRelation.errors.txt
+++ b/tests/baselines/reference/indexedAccessRelation.errors.txt
@@ -34,4 +34,30 @@ tests/cases/compiler/indexedAccessRelation.ts(16,23): error TS2345: Argument of
 !!! error TS2345:             Type 'Foo' is not assignable to type 'S["a"]'.
         }
     }
+    
+    // Repro from #31833
+    
+    type Foo1 = {
+      type: 'foo1';
+      extra: number;
+    };
+    
+    type Foo2 = {
+      type: 'foo2';
+      extra: string;
+    };
+    
+    type Both = Foo1 | Foo2;
+    
+    type FooTypes = Both['type'];
+    
+    export type FooFromType<T extends FooTypes, O extends Both = Both> = O extends { type: T } ? O : never;
+    
+    type FooExtraFromType<T extends FooTypes> = FooFromType<T>['extra'];
+    
+    function fnWithFooExtra<T extends FooTypes>(type: T, extra: FooExtraFromType<T>) { }
+    
+    type FnType = <T extends FooTypes>(type: T, extra: FooExtraFromType<T>) => void;
+    
+    const fn: FnType = fnWithFooExtra;
     
\ No newline at end of file
diff --git a/tests/baselines/reference/indexedAccessRelation.js b/tests/baselines/reference/indexedAccessRelation.js
index 643200eaf6e25..dfbb70332663b 100644
--- a/tests/baselines/reference/indexedAccessRelation.js
+++ b/tests/baselines/reference/indexedAccessRelation.js
@@ -17,6 +17,32 @@ class Comp<T extends Foo, S> extends Component<S & State<T>>
         this.setState({ a: a });
     }
 }
+
+// Repro from #31833
+
+type Foo1 = {
+  type: 'foo1';
+  extra: number;
+};
+
+type Foo2 = {
+  type: 'foo2';
+  extra: string;
+};
+
+type Both = Foo1 | Foo2;
+
+type FooTypes = Both['type'];
+
+export type FooFromType<T extends FooTypes, O extends Both = Both> = O extends { type: T } ? O : never;
+
+type FooExtraFromType<T extends FooTypes> = FooFromType<T>['extra'];
+
+function fnWithFooExtra<T extends FooTypes>(type: T, extra: FooExtraFromType<T>) { }
+
+type FnType = <T extends FooTypes>(type: T, extra: FooExtraFromType<T>) => void;
+
+const fn: FnType = fnWithFooExtra;
 
 
 //// [indexedAccessRelation.js]
@@ -57,3 +83,5 @@ var Comp = /** @class */ (function (_super) {
     };
     return Comp;
 }(Component));
+function fnWithFooExtra(type, extra) { }
+var fn = fnWithFooExtra;
diff --git a/tests/baselines/reference/indexedAccessRelation.symbols b/tests/baselines/reference/indexedAccessRelation.symbols
index c64e52a8d4d10..e2d43974203da 100644
--- a/tests/baselines/reference/indexedAccessRelation.symbols
+++ b/tests/baselines/reference/indexedAccessRelation.symbols
@@ -51,3 +51,80 @@ class Comp<T extends Foo, S> extends Component<S & State<T>>
     }
 }
 
+// Repro from #31833
+
+type Foo1 = {
+>Foo1 : Symbol(Foo1, Decl(indexedAccessRelation.ts, 17, 1))
+
+  type: 'foo1';
+>type : Symbol(type, Decl(indexedAccessRelation.ts, 21, 13))
+
+  extra: number;
+>extra : Symbol(extra, Decl(indexedAccessRelation.ts, 22, 15))
+
+};
+
+type Foo2 = {
+>Foo2 : Symbol(Foo2, Decl(indexedAccessRelation.ts, 24, 2))
+
+  type: 'foo2';
+>type : Symbol(type, Decl(indexedAccessRelation.ts, 26, 13))
+
+  extra: string;
+>extra : Symbol(extra, Decl(indexedAccessRelation.ts, 27, 15))
+
+};
+
+type Both = Foo1 | Foo2;
+>Both : Symbol(Both, Decl(indexedAccessRelation.ts, 29, 2))
+>Foo1 : Symbol(Foo1, Decl(indexedAccessRelation.ts, 17, 1))
+>Foo2 : Symbol(Foo2, Decl(indexedAccessRelation.ts, 24, 2))
+
+type FooTypes = Both['type'];
+>FooTypes : Symbol(FooTypes, Decl(indexedAccessRelation.ts, 31, 24))
+>Both : Symbol(Both, Decl(indexedAccessRelation.ts, 29, 2))
+
+export type FooFromType<T extends FooTypes, O extends Both = Both> = O extends { type: T } ? O : never;
+>FooFromType : Symbol(FooFromType, Decl(indexedAccessRelation.ts, 33, 29))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 35, 24))
+>FooTypes : Symbol(FooTypes, Decl(indexedAccessRelation.ts, 31, 24))
+>O : Symbol(O, Decl(indexedAccessRelation.ts, 35, 43))
+>Both : Symbol(Both, Decl(indexedAccessRelation.ts, 29, 2))
+>Both : Symbol(Both, Decl(indexedAccessRelation.ts, 29, 2))
+>O : Symbol(O, Decl(indexedAccessRelation.ts, 35, 43))
+>type : Symbol(type, Decl(indexedAccessRelation.ts, 35, 80))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 35, 24))
+>O : Symbol(O, Decl(indexedAccessRelation.ts, 35, 43))
+
+type FooExtraFromType<T extends FooTypes> = FooFromType<T>['extra'];
+>FooExtraFromType : Symbol(FooExtraFromType, Decl(indexedAccessRelation.ts, 35, 103))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 37, 22))
+>FooTypes : Symbol(FooTypes, Decl(indexedAccessRelation.ts, 31, 24))
+>FooFromType : Symbol(FooFromType, Decl(indexedAccessRelation.ts, 33, 29))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 37, 22))
+
+function fnWithFooExtra<T extends FooTypes>(type: T, extra: FooExtraFromType<T>) { }
+>fnWithFooExtra : Symbol(fnWithFooExtra, Decl(indexedAccessRelation.ts, 37, 68))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 39, 24))
+>FooTypes : Symbol(FooTypes, Decl(indexedAccessRelation.ts, 31, 24))
+>type : Symbol(type, Decl(indexedAccessRelation.ts, 39, 44))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 39, 24))
+>extra : Symbol(extra, Decl(indexedAccessRelation.ts, 39, 52))
+>FooExtraFromType : Symbol(FooExtraFromType, Decl(indexedAccessRelation.ts, 35, 103))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 39, 24))
+
+type FnType = <T extends FooTypes>(type: T, extra: FooExtraFromType<T>) => void;
+>FnType : Symbol(FnType, Decl(indexedAccessRelation.ts, 39, 84))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 41, 15))
+>FooTypes : Symbol(FooTypes, Decl(indexedAccessRelation.ts, 31, 24))
+>type : Symbol(type, Decl(indexedAccessRelation.ts, 41, 35))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 41, 15))
+>extra : Symbol(extra, Decl(indexedAccessRelation.ts, 41, 43))
+>FooExtraFromType : Symbol(FooExtraFromType, Decl(indexedAccessRelation.ts, 35, 103))
+>T : Symbol(T, Decl(indexedAccessRelation.ts, 41, 15))
+
+const fn: FnType = fnWithFooExtra;
+>fn : Symbol(fn, Decl(indexedAccessRelation.ts, 43, 5))
+>FnType : Symbol(FnType, Decl(indexedAccessRelation.ts, 39, 84))
+>fnWithFooExtra : Symbol(fnWithFooExtra, Decl(indexedAccessRelation.ts, 37, 68))
+
diff --git a/tests/baselines/reference/indexedAccessRelation.types b/tests/baselines/reference/indexedAccessRelation.types
index 180cff338ccc9..9079cf45d3068 100644
--- a/tests/baselines/reference/indexedAccessRelation.types
+++ b/tests/baselines/reference/indexedAccessRelation.types
@@ -36,3 +36,54 @@ class Comp<T extends Foo, S> extends Component<S & State<T>>
     }
 }
 
+// Repro from #31833
+
+type Foo1 = {
+>Foo1 : Foo1
+
+  type: 'foo1';
+>type : "foo1"
+
+  extra: number;
+>extra : number
+
+};
+
+type Foo2 = {
+>Foo2 : Foo2
+
+  type: 'foo2';
+>type : "foo2"
+
+  extra: string;
+>extra : string
+
+};
+
+type Both = Foo1 | Foo2;
+>Both : Both
+
+type FooTypes = Both['type'];
+>FooTypes : "foo1" | "foo2"
+
+export type FooFromType<T extends FooTypes, O extends Both = Both> = O extends { type: T } ? O : never;
+>FooFromType : FooFromType<T, O>
+>type : T
+
+type FooExtraFromType<T extends FooTypes> = FooFromType<T>['extra'];
+>FooExtraFromType : (FooFromType<T, Foo1> | FooFromType<T, Foo2>)["extra"]
+
+function fnWithFooExtra<T extends FooTypes>(type: T, extra: FooExtraFromType<T>) { }
+>fnWithFooExtra : <T extends "foo1" | "foo2">(type: T, extra: (FooFromType<T, Foo1> | FooFromType<T, Foo2>)["extra"]) => void
+>type : T
+>extra : (FooFromType<T, Foo1> | FooFromType<T, Foo2>)["extra"]
+
+type FnType = <T extends FooTypes>(type: T, extra: FooExtraFromType<T>) => void;
+>FnType : FnType
+>type : T
+>extra : (FooFromType<T, Foo1> | FooFromType<T, Foo2>)["extra"]
+
+const fn: FnType = fnWithFooExtra;
+>fn : FnType
+>fnWithFooExtra : <T extends "foo1" | "foo2">(type: T, extra: (FooFromType<T, Foo1> | FooFromType<T, Foo2>)["extra"]) => void
+
diff --git a/tests/cases/compiler/indexedAccessRelation.ts b/tests/cases/compiler/indexedAccessRelation.ts
index ccfcd559e2047..295979b45ae71 100644
--- a/tests/cases/compiler/indexedAccessRelation.ts
+++ b/tests/cases/compiler/indexedAccessRelation.ts
@@ -16,3 +16,29 @@ class Comp<T extends Foo, S> extends Component<S & State<T>>
         this.setState({ a: a });
     }
 }
+
+// Repro from #31833
+
+type Foo1 = {
+  type: 'foo1';
+  extra: number;
+};
+
+type Foo2 = {
+  type: 'foo2';
+  extra: string;
+};
+
+type Both = Foo1 | Foo2;
+
+type FooTypes = Both['type'];
+
+export type FooFromType<T extends FooTypes, O extends Both = Both> = O extends { type: T } ? O : never;
+
+type FooExtraFromType<T extends FooTypes> = FooFromType<T>['extra'];
+
+function fnWithFooExtra<T extends FooTypes>(type: T, extra: FooExtraFromType<T>) { }
+
+type FnType = <T extends FooTypes>(type: T, extra: FooExtraFromType<T>) => void;
+
+const fn: FnType = fnWithFooExtra;