Have you tried relogging? Some instances had a security thing and changed tokens

Clear storage and then log in once more.

Have you tried using another instance? I have that problem with lemmy.world but it is ok with less populated instances.

I gave up today and downloaded another. Regularly taking me back to the top of the page also did me in.

Jerboa sucked for me since I downloaded it. Constant logouts, unable to login after entering my creds, not showing my account until I closed and reopened the app, not letting me see my comments or saved posts, and constantly getting a "log in first" error when I tried to save a post. I ditched it and downloaded Connect, and thus far it seems to be the store-brand version of Sync, my absolute favorite Reddit app ever. When the dev releases Sync for Lemmy I will switch to that, but until then Connect is usable and pleasant.

It's been working great for me.