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: Obligatory RIP my inbox.
If it’s hashed it’s impossible to see your password (hashing is a one way process, it’s not encrypted). However nothing prevents someone from running a modded instance if they want to harvest passwords.