Federated services have always had privacy issues but I expected Lemmy would have the fewest, but it’s visibly worse for privacy than even Reddit.
- Deleted comments remain on the server but hidden to non-admins, the username remains visible
- Deleted account usernames remain visible too
- Anything remains visible on federated servers!
- When you delete your account, media does not get deleted on any server
Just as it’s impossible to stop scrapers from archiving data on traditional websites. “Deleted” data is probably in a database somewhere, being sold by someone. As you said, you lose some degree of control over your data as soon as you post it. Data is valuable, and if there is a will there is a way.