privacy.restrict3rdpartystorage.skip_list unavailable in about:config

### MDN URL

https://developer.mozilla.org/en-US/docs/Web/Privacy/Guides/State_Partitioning

### What specific section or headline is this issue about?

Exempt specific origins from partitioning

### What information was incorrect, unhelpful, or incomplete?

The pref 'privacy.restrict3rdpartystorage.skip_list' is unavailable in about:config.
Setting it via user.js doesn't work.
The doc says it can be set, but doesn't say how.

### What did you expect to see?

An explanation of how to set the pref.

### Do you have any supporting links, references, or citations?

_No response_

### Do you have anything more you want to share?

_No response_

### MDN metadata

Page report details

* Folder: `en-us/web/privacy/guides/state_partitioning`
* MDN URL: https://developer.mozilla.org/en-US/docs/Web/Privacy/Guides/State_Partitioning
* GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/web/privacy/guides/state_partitioning/index.md
* Last commit: https://github.com/mdn/content/commit/273c94d6c22ee0084a5de9c5adba8f94d8d01444
* Document last modified: 2025-09-23T19:53:04.000Z