The best part of the fediverse is that anyone can run their own server. The downside of this is that anyone can easily create hordes of fake accounts, as I will now demonstrate.
Fighting fake accounts is hard and most implementations do not currently have an effective way of filtering out fake accounts. I’m sure that the developers will step in if this becomes a bigger problem. Until then, remember that votes are just a number.
Maybe adjust by the number of upvotes coming from that instance (negatively) and by the number of upvotes users of your instance give over their (positively). If one instance spams upvotes, these upvotes loose value. If posts on that instance are popular with your users, the upvotes coming from that instance are more likely to have been made by real users. Maybe we can find a better metric to estimate the number of real, active users on another instance.
Sounds interesting, imilar to the way googles page rank works.