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
Apple (and Google, Microsoft, etc) are checking signatures of all files on their services to detect illegal stuff. They do it for copyrighted content and they do it for CSAM.
Checking against a known-malicious hash is very different than claiming to have access to the plain data. In fact, even for the known-malicious hashes, the companies doing the checks usually don’t have access to the source data (so i.e. they don’t even necessarily know what it contains, just that it’s not allowed).