At one point it was possible to download every reddit comment ever. I think it was around 10 years ago I had a copy of that. I can’t remember if it was from reddit directly or from some third party with scrapers. I recall the dataset being free… but it might have been free for me because I had an academic justification? Really don’t recall.

Anyways, point being that you’re delusional if you think anything you post online ever goes away. Secondly, you can be much less than palentir and have “deleted reddit account comments”. Anyone can get them.