Edit: obligatory explanation (thanks mods for squaring me away)…
What you see via the UI isn’t “all that exists”. Unlike Reddit, where everything is a black box, there are a lot more eyeballs who can see “under the hood”. Any instance admin, proper or rogue, gets a ton of information that users won’t normally see. The attached example demonstrates that while users will only see upvote/downvote tallies, admins can see who actually performed those actions.
Edit: To clarify, not just YOUR instance admin gets this info. This is ANY instance admin across the Fediverse.
Essentially you’re giving away a lot more info about yourself than you might realise. If someone who takes an unfriendly interest in you wants to, they can probably find out a lot more info about your habits, likes, dislikes, interests, political views, waking hours, etc than just what you’ve publicly commented!