That's strange. I use a yubikey under Linux/FF and it works like a charm and has done so since I started using them years ago.

Well, mine doesn't work, so I'm still using Chrome. When they make it work, I'll switch to Firefox. There should really be a big fat "report bug" button on all these apps that captures logs and sends it with 1-click permission and a voice recording to explain what's wrong, like Tesla FSD's bug reporting system. I don't have bandwidth to deal with their community forums and all the crap it takes to register for them.

Both yubikes and gotrust idem kyes also work for me just fine. Maybe i am using them just for fido 2 factor and not some of the other protocols?