Ctrl+Shift+A will get you to Add-ons and Themes. Click on Extensions, if it is not already chosen. Among your extensions you should see relay. Click the switch to the right to turn it off or the three dots to remove it completely.
It's not installed, but thx. I already solved it in another comment
I'm fairly sure that that's unintentional behaviour. I reported it here, but if you have additional info to share there (e.g. your browser version), that would be fantastic: https://bugzilla.mozilla.org/show\_bug.cgi?id=1870820
Wow! Thqnj you!
Unfortunately I am away from keyboard til Winter solstice. It's the latest flatpak, i.e. 120 . 121 j usda t got released,,,,, that's unlikely it.