How does this compare with Carrot?

Why do you think that?

This seems transparent, well thought out, and opt-in. The headline concerned me but once I read the article this seems fine. I moved from LastPass to 1Password because of the horrible communication around breaches in the last few years.

A sketchy instance operator isn’t really a solid defense against implementation of better privacy features in the source code.

Deleted comments remain on the server but hidden to non-admins, the username remains visible

This is a negative behavior by Lemmy, in my opinion. Deleted comments should be purged after some time. Tildes does the same thing - I think with 30 days?

Deleted account usernames remain visible too

These should be replaced with some random string of characters or something like DeleteUser<numberhere> or something.

Anything remains visible on federated servers!

This is just a concession of federation.

When you delete your account, media does not get deleted on any server

This is an issue, too, in my opinion.

Maybe platforms collapsing is a feature and not a defect. I moved from Digg to Reddit and felt no great loss that Digg no longer exists years later.