In my case:

feddit.de didn’t update and as soon as I switched to another account I couldn’t login again

So I created one on shitjustworks. (which ended up with the same problem, but I wouldn’t want to have a third sfw-account so I just waited until it resolved)

And I wouldn’t be surprised if there was another old account of mine on feddit.de from a time where lemmy was just this weird thing some people in r/berlin linked to