Yeah, the Lemmy 2FA implementation sucks. It only works in certain authenticators - Authy not being one of them. Google Authenticator does work and apparently so does the iOS keychain (but can't confirm that one).

Best way to do it is to enable it and set it up but keep the settings window open, then open a separate incognito window and try to log in. If your 2FA code doesn't work, go back to the other settings window and disable it.

I'm surprised I haven't seen more posts yet about this. A rogue or compromised admin put JavaScript redirects on Lemmy.world as well as changed the name and some other things. The other admins removed the compromised admin, but then about 30 minutes later they were reinstated and started wreaking havoc again. The instance eventually went offline completely.