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’m pretty sure editing the email removes the record. In general, editing updates the database with the new value while deleting things marks a record in the database as deleted (e.g. so a mod can un-delete something that was accidentally deleted by a mod). Editing the email adress to remove it should just clear that field in the database. Of course your instance will have backups, but they won’t keep them forever.
Things are moving faster and faster these days! I’m not sure that anyone keeps up with everything new.
You’re not the first person to make that connection!