This pisses me off. YouTube has gone out of their way to block picture-in-picture. Each time Apple released an update that made it work, you could use it on the YouTube website in Safari. Within a day YouTube made changes to their site to break it. When you open picture-in-picture, their JS detects that and ends the video. This is not accidental, it is very much on purpose.
People in this thread are saying it works on Android. If that’s true, it’s an even bigger violation.
Apple is being made a fool of, and I can’t believe they haven’t done anything about it.