Don’t know if it is expensive for reddit but the link works at the time of this posting.
I can help you if you want. I suggest using Power Delete Suite to first overwrite and then delete your history, and then making the suggested data request.
Reddit keeps undeleting that though, even if you’ve been using reddit from an EU ip all the time (which would mean you are protected by GDPR)
PDS doesn’t include rate limit controls, so Reddit will start rate limiting you after just a few requests. This results in PDS telling you that it deleted content that it did not delete (partially because Reddit returns 200 error codes while ALSO including a message that your request was rejected).
I modified the PDS source to delay 2000ms between requests and ran it via ViolentMonkey in Firefox. It took a couple of days to run, but that did the trick.
TL;DR: Power Delete Suite is currently broken and it’s likely your content was never deleted in the first place.