No API required. Kinda slow, but just leave it running overnight if you have a lot. Make sure you run it from https://old.reddit.com/u/me/overview
A python script hooked up to the openai API could be a fun way to play with this. Just edit the comments with random bs somehow marginally related to the original topic but incorrect.
It’s a real shame though because those old comments are often lifesavers when you’re looking into really niche subjects.
I was thinking about manually editing every comment to replace them with lorem ipsums and similar rubbish text, I wonder if they would mark that as “suspicious activity” and lock me out of my account? I read some people in the past had similar issues with mass deletions or edits.