fix(plugin): support ytAtN attestation format for initial attestation extraction

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed: Initial attestation extraction from YouTube webpage by adding support for the new `window.ytAtN(...)` format alongside the legacy `window.ytAtR = ...` format (plugin v1.3.0)
+
 ## [0.7.1] - 2026-02-18
 
 ### Fixed

plugin/yt_dlp_plugins/extractor/getpot_bgutil.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-__version__ = '1.2.2'
+__version__ = '1.3.0'
 
 import abc
 import json
@@ -52,28 +52,32 @@ def _warn_and_raise(self, msg, once=True, raise_from=None):
     def _get_attestation(self, webpage: str | None):
         if not webpage:
             return None
-        raw_challenge_data = self.ie._search_regex(
-            r'''(?sx)window\.ytAtR\s*=\s*(?P<raw_cd>(?P<q>['"])
-                (?:
-                    \\.|
-                    (?!(?P=q)).
-                )*
-            (?P=q))\s*;''',
-            webpage,
-            'raw challenge data',
-            default=None,
-            group='raw_cd',
-        )
-        att_txt = traverse_obj(
-            raw_challenge_data,
-            ({js_to_json}, {json.loads}, {json.loads}, 'bgChallenge')
-        )
-        if not att_txt:
-            self.logger.warning(
-                'Failed to extract initial attestation from the webpage'
-            )
-            return None
-        return att_txt
+        raw_cd = (
+            traverse_obj(
+                self.ie._search_regex(
+                    r'''(?sx)window\s*\.\s*ytAtN\s*\(\s*
+                        (?P<js>\{.+?}\s*)
+                    \s*\)\s*;''',
+                    webpage,
+                    'ytAtN challenge',
+                    default=None),
+                ({js_to_json}, {json.loads}, 'R'))
+            or traverse_obj(
+                self.ie._search_regex(
+                    r'''(?sx)window\.ytAtR\s*=\s*(?P<raw_cd>(?P<q>['"])
+                        (?:
+                            \\.|
+                            (?!(?P=q)).
+                        )*
+                    (?P=q))\s*;''',
+                    webpage,
+                    'ytAtR challenge',
+                    default=None),
+                ({js_to_json}, {json.loads})))
+        if att_txt := traverse_obj(raw_cd, ({json.loads}, 'bgChallenge')):
+            return att_txt
+        self.logger.warning('Failed to extract initial attestation from the webpage')
+        return None
 
 
 __all__ = ['__version__']