Cant login to Firefox Sync in LibreWolf

This might not necessarly be an Issue with the NixOS Package of Librewolf.
I enabled Firefox Sync in about:config setting the option identity.fxaccounts.enabled to true, but i cant login to the Firefox Account after that. It will show “working…” forever.

Anybody got a workaround for that? I have searched for a solution and messed with about:config values for hours now. Also tried the unstable package of LibreWolf.

Im Running NixOS 23.11