Clear the app cache, that did it for me.

If it doesn't work, clear the data too.

I don't think it's entirely the app. I've had it happen to my Lemmy.world account using Jerboa and Connect, so I think this must be them working on stuff after the hack.

I think this is related to the recent security vulnerability that affected, notably, lemmy.world. Even unaffected instances mostly decided to invalidate existing user sessions just to be sure and this required resetting Jerboa and some other apps that presumably hold onto a cached version of your auth token even if you remove the account and re-add it or something. So it was necessary to clear the app cache and storage to reset it and add accounts again.

I think it's a lemmy.world issue. Happens in Connect too.

I had that last night but it seems fine this morning. I made accounts at mastodon and lemm.ee so I could still get info on when things were back up and running on .world

This is due to having your session invalidated after that exploit that hit lemmy.world decently hard.

Delete your user, and readd worked for me. Alternatively clearing the apps cache I've heard can work.

Remove and reinstall would also work, but is just a more roundabout way of the other two methods.

Technically, it does show a gap in Jerboa to me. It can't handle the unexpected scenario of server side invalidation of login sessions.