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.
Your IP would only be seen by your instance (which is inevitable, you gotta connect to it after all). But there’s no way for anyone else to look up your IP.