Deleting a post is simply marking a piece of text so nobody sees it, but I think the text is still stored in their servers.
Furthermore, a large company like reddit, must backup regularly, meaning there must be several copies of my posts in several SSDs. If the backup once a day… some of my posts are 5 years old.
Companies exist to make money. I suspect they just marked my posts not to be readable by anyone, except staff and they can still monetize them.
Am I wearing a tinfoil hat way too often?
The short answer is: Yes, they can still monetize what you posted, and there’s nothing you can do about it.
(And no, the GDPR doesn’t apply, they can just strip away the associated username and IP address)
Depending on what they do it’s not that simple. If you include the entire history of an account you could probably de-anonimize most active users. That being said, de-correlating the comments and posts before feeding them to an AI model is probably enough.