The api is still open, but you can't exceed 100 per minute per "Reddit app" unless you pay. So if you want to delete your entire post/comment history, you'll need to Register a new app and it will take some time to delete everything. At least that's how I understand it.
My Reddit GDPR Request took 20 days, this is what it looks like (kbin.social)
Account was from 2011 with almost 5000 comments....