It’s not a fix but a little work around if you don’t want to reinstall:
Edit your password and just re-enter it, then tap save. Seems to achieve the same thing as reinstalling to get a new Auth token.
Agree totally with the feedback Re no information on authentication being dropped. A little splash banner or something would suffice, and then the ability to try authenticating with stored creds again
I see this same issue every now and then on lots of different places, and now it’s happened to me. I think I remember someone saying it happened after their instance got a Lemmy update?