Reddit can restore your deleted posts. However, if people flood them with GDPR / CCPA delete requests, they may become liable for lawsuits if they don’t comply.
It sounds like their current policy is to not delete your posts even when deleting your account, but there may be grounds for legal action here.
https://www.reddit.com/settings/data-request You can first request them to give all of your reddit data to you. After that you should be able to contact or reply to that message demanding them to delete it.
Has anybody had success with this recently? My recent GDPR request is almost a week old and still no answer, used to take less than an hour last time I tried it.