Nice play, I already wondered why the page does not load.
So the two biggest issues seem to be:
Voting is public (but invisible to users who are thus oblivious about it)
Post/comment history is public, entirely
I’m not sure if (1) can be changed regarding the ActivityPub protocol, but I would appreciate it. There is at least a communication issue since most users probably expect votes to be anonymous.
A shallow research made me hope something like zk-SNARK could be a solution. Voters must be able to identify themselves (to revoke or change their votes later), but servers must be unable to track individual users across multiple votes. A lesser, but still desirable achievement could be to make it impossible to track individual voting behavior across multiple servers.
Agree to @mojo about (2). It should be possible to restrict how much of my post history others can see. On the other hand, crawlers and scrapers could still gather the data from browsing publicly available posts and comments, and reconstruct individual post histories. This would then resemble (1) again; users expecting some privacy when they actually have not.