I searched a bit through the documentation and code and these were my findings. I thought I'd share them for others that are interested and for future reference

I searched a bit through the documentation and code and these were my findings. I thought I'd share them for others that are interested and for future reference. Currently, there are no domains blocked, they would appear on this API endpoint: https://firefox.settings.services.mozilla.com/v1/buckets/main/collections/addons-manager-settings/records https://firefox.settings.services.mozilla.com/v1/buckets/mai... This is the json schema for this API endpoint: https://firefox.settings.services.mozilla.com/v1/buckets/main/collections/addons-manager-settings https://firefox.settings.services.mozilla.com/v1/buckets/mai... More information on the remote settings in general: AMRemoteSettings Overview - quarantinedDomains: https://firefox-source-docs.mozilla.org/toolkit/mozapps/extensions/addon-manager/AMRemoteSettings-overview.html#quarantineddomains https://firefox-source-docs.mozilla.org/toolkit/mozapps/exte... Remote Settings documentation: https://remote-settings.readthedocs.io/en/latest/index.html https://remote-settings.readthedocs.io/en/latest/index.html Remote Settings Devtools - where you can see all the remote settings, that get set: https://github.com/mozilla-extensions/remote-settings-devtools https://github.com/mozilla-extensions/remote-settings-devtoo...