I daily drive Firefox as my browser, maybe it's an issue with the branch? I've never had this issue myself. On the rare occasion that that it doesn't properly detect password field I can just right click and shows as a menu option that I can fill password fill TOTP or email, I've never had it just not work at all. Excluding mobile, but that's strictly an issue with how Android does Auto filling because they can't have the service that fights to do both and since Firefox has its own autofill service it's a coin flip of whether or not it uses keypass or Firefox built in password manager