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?
“This post has been moved to Lemmy at url xxyyzz, fuck spez” would keep the info around, if that makes you feel better.
That should be the only way, but I seriously doubt that Reddit admins would keep the links intact in that case. Out of their greed and malice they would probably mess with the Lemmy link, then put the blame narrative on the poster for deleting/making the information unavailable.
It can be a bit annoying like how c/hackernews post only external links with topic titles, but that is the (temporary) cost of freedom and privacy.
Maybe you’re right but at least you will have tried.