I do the same, and after a day of doing it- they seem to go away for a time depending on the platform, but they always come back and sometimes they come back a lot.

The web-browser is the least aggressive and I think I haven’t even seen them on Apple TV.

The iPhone App is the most egregious offender of not respecting the request though, it seems to almost not care at all, and now the thumbnails on the home screen have started autoplaying (with audio) and I can’t find how to disable it (older instructions seem to be invalid).

They have all the content though; so I have no choice but to deal with this, until a good enough competitor comes along and my favourite youtube channels upload to both places.

Auto play with audio needs to be controllable for accessibility. May be a regulatory requirement depending where you live. So it’s gotta be there somewhere.