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.
I’d dare say lemmy creators wouldn’t mind private votes, they chose not to display voting counts to normal users after all, but that’s not how the ActivityPub protocol is built and honestly can’t be built if you want federated votes.