also, you could modify subscription counters so you had a count of subscribers from an instance without knowing who they were.
what is the problem with votes btw? Someone else just mentioned those should be private too in the chat where I first raised this.
There, you've already found a reasonable way around it! 😀
lets take community subscriptions specifically. Here's a handful of rows from community_follower with my person_id. Why couldn't you hash community_id with my public key and then I provide my private key to whatever ui client I'm using to populate my feeds when I log in?
the point is not to encrypt your user id, check this out if you haven't seen it I think I explain it better here: https://lemmyadmin.site/comment/46. It's a lot more privacy. And thinking as an admin that wants to provide a safe space for my users, I think it's worth the effort. I took a very quick look at the tables related to person and I'd bet you could treat these similarly to community_follower: