It stopped working. Now it does not do anything useful regardless of any settings at all and the on/off switch missing. Deleting and reinstallation with default settings didnt help. What did actually help is installing an older version of AdGuard.
So, earlier versions of AdGuard do work though. Considering this fact, the faulty thng is not the browser, but the latest version of AdGuard.

It just stopped blocked any ads. Basically useless now

nickel...

1. super system, should be 5 stars but:
2. except that their DNS is in conflict with FF settings. I am NO specialist, just make it work please.
3. settings you put in the main is not snc with other settings in FF or Edge etc.

BEI DEM TEXT "WebRTC deaktivieren
WebRTC kann Ihre IP-Adresse lecken," USW. SOLLTE STEHEN "leaken" VON "to leak" ODER ES IST "ein Leck verursachen" GEMEINT - lecken (undicht sein – schwaches Verb): durch ein Leck Flüssigkeit herauslaufen lassen ; lecken (sich widersetzen – schwaches Verb) [Duden]

The better

Please introduce a toolbar shortcut! This is the only minor issue I do have with the AdGuard extension: The time needed to disable and re-enable it, as it otherwise is a huge time saver and very much worth in it doing what it promises.
Otherwise it is an unbeatable extension to stop annoying ads on Firefox appearing even avoiding lags while playing videos. Sorry, YT, but your new ad policy just became to annoying. I turn the blocker from time to time, just to see, whether you got a little more sense of the issue - and I disable the extension when using other sites than YT.