[Bug]: Unable to disable Firefox's shortcuts and define custom shortcuts.

[littleapple-juice]

Pre-Submission Checklist

• [X] I have checked the existing/closed issues to ensure this issue has not already been reported.
• [X] I am using the latest supported version of the browser.
• [X] I have tried disabling all browser extensions/add-ons to rule out interference from these.
• [X] I have tried clearing the browser cache and cookies.
• [X] I have checked with a new profile and the issue still occurs.
• [X] I have provided detailed step-by-step instructions on how to reproduce the issue.
• [X] I have included relevant screenshots or console outputs.
• [ ] I have checked this problem is not occurring in the latest version of Firefox ESR.
• [ ] This issue is specific to this browser and does not occur in other browsers.

Bug Summary

Cannot set custom shortcuts since disabling Firefox's shortcuts won't work and the option just reverts back to unchecked.

Reproduction Steps

1. settings
2. keyboard shortcuts
3. check "disable Firefox shortcuts"
4. restart

Expected Behavior

Can set custom shortcuts.

Actual Behavior

Disabling Firefox shortcuts is not working after restart.

Screenshots

Browser Version

11.14.1 (64-bit)

Operating System

Windows 10

Additional Context

I also downloaded portable version, but the issue persists.