Happened to me too yesterday I had many alt and my account where I do European activism got shadowbanned so I decided to delete everything but they would not let me, the only way is to cause mayhem and break the rules to make them regret keeping you.
Just send a GDPR deletion request.
You can find ready made texts online. Just plug in your email/username and send it. Make sure to request a confirmation of the deletion.
it's not just Reddit. it's more websites every year.
I've worked as a sysadmin at companies who have done it. they blacklist an ASN which covers an entire ISP, or they just straight up ban the entire country. it's the easiest way to get rid of a few kids running penetration scans against the site or whatever. they don't get much revenue from the users in these countries and so they don't care. access to the collective knowledge of humanity is always getting smaller in developing countries.
A few months back someone posted that they found all of their deleted posts from when the great migration to Lemmy happened. And I checked myself that day and found that a large portion of my posts that I had deleted were restored. And I had verified the day that I had left Reddit that my posts were gone. There was no history on my account. And if I look right now those posts exist again.
I recommend using a tool to scramble all of your comments, waiting a while, and then deleting. Check back every few days to verify deletion before ultimately closing your account. For some reason, if a subreddit is hidden or closed, you can delete your messages from there until it's reopened.
I spent about 2 weeks deleting my accounts from reddit during the mobile app exodus.
I remember it using the API, which is supposedly disabled now. There are warnings on early Lemmy posts to use the tool before Reddit rolls out the changes.