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 think you need to clarify how they can see the password. It’s not stored in plaintext, but when the user logs in, the server administrator can see the password in the HTTP post data if they log it in the lemmy sourcecode. All apps are subject to this and it’s why to have to trust the instance owner.
and also the reason not to reuse passwords