I do think the quality has gone down over my seven-ish years on HN, but that could be me just remembering "the good ol' days". Still so much better than Reddit though. It's not close. Reddit has a much lower quality set of posts and comments on average across technical subreddits.
I remember the Ivermectin/Hydroxychloroquine fights where people were gaslighting others for some unknown reason. People sharing dubious studies, with questionable results.
Meanwhile many of those people had a secondary agenda to keep the FDA from releasing the covid vaccine. America's Frontline Doctors (the group) promoted drugs over vaccines, etc.
Granted there was a lot of fear in the air back then. But this site is not immune from toxicity.