These rumors of restored comments have been going on since the start of the reddit blackouts. And they're largely not happening anymore now that the blackouts are over. It was the blackouts. I checked my comments and deleted new ones almost every day during the blackouts, and whenever they "came back" they were all on a previously-private sub and they "came back" as a bloc. It was private subs having comments be private, then turning public/restricted and "restoring" the previously-inaccessible comments.
Literally just one confirmed case of someone who knew about the "restorations" and took some kind of backup before deleting to prove it happening. Just one case. But there isn't.
There is absolutely zero chance Reddit would be restoring only certain comments. It would be widespread if they were doing it. They aren't going to send out one of the professional sitewide mods with admin tools to review deletions and randomly restore only certain comments.