This is anecdotal, but I don't experience these log outs on fedia (I have to relog like once every few days but that doesn't bother me, I assumed it was cookie expiry but maybe it has to do with server restarts or something). So I can understand if it happens more often to kbin social users it might be some other way it's set up like caching or something that others might not be running. Then again, without version info, it makes it a bit tough to debug so this might not be helpful, fedia could be running some random sha atm which might be the reason.