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.
That information is not tracked in the application itself. A “home instance” admin could correlate their web access logs with the database to draw this kind of conclusion but it’s not federated info.
That’s good at least. This means that I only need to trust the host for my home instance keep my anonymity.