Its a bug where it fails retrieving the account info, it makes it look like ur not logged in. It's more notable recently because instances are having more issues.
Strange I just tried reproducing this but i was unable to do so. Does it only happen in Jerboa? Maybe a powersaving feature of your device is causing it. I think I might have idea to fix this. You will have to make an issue on github with your specific device and anything relevant. And then I can send you some test builds to see which resolves it.
That button has never done anything, it's functionality has yet to be implemented. There is draft in working, when ever that gets finished it will be in Jerboa.
The navigation buttons resetting the navigation History is currently the intended behavior and not a bug. I am adding a back confirmation feature, that should be in 0.39 or 0.40. If more users prefer it not to do the nav resetting, i suggest making a issue to amend this, so that we can properly weigh in the desired behavior by the majority of the users.
Make a issue with your crash logs on github. I can't reproduce this, so it is probably something device/ android version specific. So the logs are really important.
Its a bug where it fails retrieving the account info, it makes it look like ur not logged in. It's more notable recently because instances are having more issues.