From Lemmy documentation:
We don’t delete anything from our database, just hide it from users. Deleted or removed Communities/Posts/Comments have a “restore” button.
But don’t take my word for it. Try it out yourself. You can make a comment, delete the comment (your username appears to remain) and then restore its content.
I’m guessing this is why every reddit purge scripts edit the content first and then remove, right?
Correct.
From what I understand, Reddit started keeping an edit history a few years ago to counteract those scripts.