@Michael2413 @Lizzie
I don't think it's a password change issue. This has just started for me, having turned my phone off yesterday. When I turned the phone back on, i couldn't log into either the app, or through a browser (Firefox Focus) on the phone. Still able to log in on my laptop, though. It seems to have something to do with Captcha, which began appearing at log in (and is "buggy" even on my desktop).
Have sent feedback (obvs), but it sure would be nice to get an official update on what's happening!