For what it's worth, Most Pleroma instances that have seen your posts will serve them to anyone, even if you delete your account. And that cache never expires, IIRC. Have fun.
(BTW, there's a link to a tool that does just that in the previous post, Mastodon has really bad contrast on links and I keep forgetting. https://puckipedia.github.io/pleromancer/)
@puckipedia wait this also works for deleted posts? oh geeze