A derived value sometimes loses its reactivity

[hironytic]

Describe the bug

After upgrading to 5.16.1, I noticed that a derived value sometimes loses its reactivity in my project.
I couldn’t find the exact trigger though, I could find reproduction steps in a minimal code in the playground.

Reproduction steps:

1. Click “d” button, then current id changes to 4, and name to d.
2. Click “Show / Hide” button, then the content above is hidden.
3. Click “Show / Hide” button again, then the content is back.
4. Click “c” button, then current id changes to 3, and name to c.
5. Click “b” button, then,
   • Expected behavior: current id changes to 2, and name to b.
   • Actual behavior: current id changes to 2, but name doesn’t change.

Reproduction

https://svelte.dev/playground/c10266b02aab40e58b93a9545c8ac639?version=5.16.1 (Reproducible)

https://svelte.dev/playground/c10266b02aab40e58b93a9545c8ac639?version=5.16.0 (Work as expected)

Logs

No response

System Info

System:
    OS: macOS 15.2
    CPU: (8) arm64 Apple M2
    Memory: 133.42 MB / 24.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.15.0 - ~/.volta/tools/image/node/20.15.0/bin/node
    Yarn: 1.22.19 - ~/.volta/tools/image/yarn/1.22.19/bin/yarn
    npm: 10.7.0 - ~/.volta/tools/image/npm/10.7.0/bin/npm
    pnpm: 9.6.0 - /opt/homebrew/bin/pnpm
  Browsers:
    Chrome: 131.0.6778.205
    Safari: 18.2
  npmPackages:
    svelte: ^5.16.1 => 5.16.1

Severity

blocking an upgrade

[Leonidaz]

@trueadm looks like a change in the #14855 is now causing this bug.