Problem with Mull and Duolingo - eviltoast

Hello, I started to experience a problem with Mull and Duolingo (and also bromite) that started about 1 month ago.

Basically Duolingo tells me that my browser is not supported but it worked perfectly fine before. Anyone experienced this issue? I can’t find an issue on mull repo apparently about this specific issue. Dunno if it is something about resisting fingerprint but I wonder why that happens…