Abrowser disallows browser extensions from executing on Mozilla domains

Steps to reproduce

1. Create a fresh Abrowser profile and launch it in new browser window.
2. Navigate to about:config.
3. Look up the extensions.webextensions.restrictedDomains preference.

Expected behavior

extensions.webextensions.restrictedDomains is by default set to an empty string to allow users to use extensions on Mozilla websites, including for the purpose of blocking nonfree JavaScript there.

Experienced behavior

extensions.webextensions.restrictedDomains is by default set to:

accounts-static.cdn.mozilla.net,accounts.firefox.com,addons.cdn.mozilla.net,addons.mozilla.org,api.accounts.firefox.com,content.cdn.mozilla.net,discovery.addons.mozilla.org,install.mozilla.org,oauth.accounts.firefox.com,profile.accounts.firefox.com,support.mozilla.org,sync.services.mozilla.com

Reproduced on

Abrowser 96, 97, 98

Notes

Additionally, even manually clearing the preference does not take effect. Abrowser silently ignores the change and still stops extensions from executing on Mozilla domains as if the preference was still set to its default value.

This was previously reported at https://trisquel.info/en/issues/28767 or https://trisquel.info/en/issues/28768 but unfortunately, both issues are inaccessible now