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.
Isn’t this kind of how comments works too tho? You can tell who it is by how they write and you can see what they do care about and when they are active. I assume comments are worth more than just a up vote or down vote. So the votes could also just have been a log in the comment section “x likes this post”. It is good you said it tho so ppl know that votes aren’t anonymous.