I use yt-dlp to download sporadically some YouTube clips and it works fine.
However, once I attempted to download a complete YouTube list of clips, with a total size of several tens of GB. Towards the end of the list, after a couple of hours or so, the download was interrupted.
Then my IP address was completely banned for YouTube, regardless of the browser used. The ban lasted for a couple of weeks.
Now, used only for infrequently downloading single clips, yt-dlp works again fine.
They likely want to block alt clients that strip adverts while allowing the small amount of downloading to still work.
Well, the big G is not going to sit around and watch it being scraped
Obviously, the YouTube team is aware of yt-dlp, and with Google's engineering density, a small team can completely block it & win in the cat-n-mouse game against community volunteers that make all their code public.