Been lurking but saw this thread and had to make an account to try and set the record straight, as there's a lot of misinfo on this on Reddit, too.
If a subreddit turns to private and you are not a moderator or an approved submitter, all the comments and posts you have made in that subreddit will disappear from your profile. If you then delete all your comments, once the subreddit returns to being public again, those comments will then show up on your profile, because those comments couldn't be deleted while the subreddit was private.
That's all that's happening. You nuked your profile within the past few days and there was nothing left. Problem was, half of the subs you comment on were private, so the nuking app or script was not able to delete them. Now that they're all coming back, your profile shows a whole heap of comments again, but they're not the same comments. The ones you deleted are still deleted.
Yes. It's just people seeing comments from now public subs return to their profiles again and mistaking them for comments they thought they had already deleted/edited.