as instance admins, they have access to the database, so they straight up can edit any data.
only thing they can't do is view your password (hashed), but they can replace the hash by one of a known pw.
so you must have some trust in your instance owner, again whats good with the fediverse is that you can just start your own instance, and then the best they can do is defederate from you or ban you.
i don't think he has time to waste on that, he too busy thinking of more ways to fuck up reddit.
as instance admins, they have access to the database, so they straight up can edit any data.
only thing they can't do is view your password (hashed), but they can replace the hash by one of a known pw.
so you must have some trust in your instance owner, again whats good with the fediverse is that you can just start your own instance, and then the best they can do is defederate from you or ban you.