Re: Downvote bots. I can’t say they’re necessarily bots, but my instance has scripts that flag accounts that exclusively give out downvotes and then bans them. That’s about the best I can do, at present, to counter those for my users.
It is usually not a good idea to specify what your exact metrics are for a ban. A bad actor could see that and then get around it by randomly upvoting something every now and then.
Only issue I see is that the 8 chars required is very short and easy to brute force. You would hope that people would go for the recommended instead, but doubt it.