Fair warning, I used PowerDeleteSuite and Reddit seems to have backfilled a bunch of deleted comments while keeping them off my user page. Every now and then I'll read an old thread and see my username and have to manually delete the comment.
God, that is just the WORST concept especially nowadays. I was looking for info on water filtes and found a bunch of ChatGPT comments from 3 months ago on an 8 year old thread shilling for some company. Of course, they were all upvoted to the top of the thread.
I even had a notification of someone just commenting "lol" on an offhand comment I made about Firefly in 2011. As if that needed to be said.
Sorting by "controversial" does, though, show new comments that weren't on the main page. So you might be on to something.
My theory was Reddit ran batch jobs on some cadence (daily maybe?) to generate the topN comments lists for each users profile page. Running my script a couple of times over a several days seemed to clear everything.
I'd love to delete old comments on HackerNews but I can't so I'm pretty sure that Reddit could take away the delete button tomorrow and nothing would change.