OK, I figured it out: password length Not sure what was changed on Lemmy overnight, but my password suddenly became too long for FF, Chrome, and even Liftoff.
During my trial and error checking, I tried changing the password (which continued to work in Edge), but suddenly Liftoff would not accept the new one. Changed it to something ridiculously short and miraculously everything worked in all the browsers and Liftoff. Inched it back up to something acceptably long and complex again.
Someone already posted this somewhere. It’s a second stage from a rocket (India?). Can’t recall the exact one.