So you can get the users voting on posts on other instances?
Could it be anonymized, so you can get exact up/downvote data from your instance, but when it comes to other instances you only get the absolute up/downvotes?
So any instance admin can analyze all users upvotes/downvotes and possibly derive political standpoints, likes/dislikes, opinions and location data from it
I agree, someone has to store and maintain your data, but giving all instances access to it is a risk that could be avoided