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.
I do not believe upvotes and down votes are enough information to reveal the identity of anyone. If this was truly such a risk, where has the concern for this been on Facebook, where you can see who leaves reactions by name. Or Discord where every account that clicks a reaction is available?
Here that info is not available to the public at large. On Facebook it’s available to anyone who sees a post. Why haven’t security voices been pressuring Facebook to not track social reactions if it’s so dangerous?
This is a feature of social media for the most part. What I write as posts and comments is available to everyone as is vastly more useful info for someone to collect.