Ask HN: What Happened to YouTube Recommendations?

There are lots of reports of YouTube recommendations suddenly getting much worse, e.g. on /r/youtube from the past 3 days: https://www.reddit.com/r/youtube/comments/sg57kl/a_very_strange_home_page/ https://www.reddit.com/r/youtube/comments/sg2qnd/weird_recommendations/ https://www.reddit.com/r/youtube/comments/sfdwyh/algorithm_gone_insane/ https://www.reddit.com/r/youtube/comments/sfczuh/has_anyones_youtube_recommendations_randomly/ https://www.reddit.com/r/youtube/comments/sfaaij/horrible_recommendations_as_of_12722_6pmest_any/ https://www.reddit.com/r/youtube/comments/sexhtp/youtubes_recommendations_are_still_broken_that/ https://www.reddit.com/r/youtube/comments/settip/anybody_knows_what_in_the_hell_happened_to_my/ https://www.reddit.com/r/youtube/comments/ses7u7/what_happened_to_my_recommendations/ https://www.reddit.com/r/youtube/comments/sekomo/i_clicked_something_and_now_my_youtube/ https://www.reddit.com/r/youtube/comments/se5op4/youtube_recommendations_going_crazy_since/ https://www.reddit.com/r/youtube/comments/sdmble/weird_youtube_recommendations/ https://www.reddit.com/r/youtube/comments/sdnykp/youtube_recommendations_broken/ It seems that things got worse 4 days ago, when YouTube made Watch History a requirement for showing any recommendations. I couldn't find any mentions of recommendations being broken in the few days before that on /r/youtube. Anecdotally, in the past week my recommendations became a mix of awful generic videos, with almost no personalization. Does anyone know what's going on?