I recently learned that voting on lemmy is not anonymous. Anyone can get information about who has upvoted and downvoted a post or comment.
In combination with your IP, this is a massive privacy (maybe even physical security) risk. Also, people can target you for your votes.
Sadly, this is something where I would prefer Reddit over Lemmy. Big tech scrapes data from both places anyways, at least Reddit is safe.
If you run your own Lemmy server, you can probably just query your server’s database. Lemmy admins can see upvoters and downvoters for all comments (and posts I think), not just comments/posts on servers they’re an admin on, so that data must be in the database.