I’m surprised they didn’t do this sooner... now mine immediately pops back into the viewer the instant I tap the PiP icon. I was so happy during the beta series with this feature. I even got used to using the desktop site in Safari. That’s stupid that Apple allows them to detect if the video is playing in PiP and disable it, if that’s the case here. YouTube is now blocking a native feature of the device in the browser. That’s ridiculous. They might be able to get away with that in the app, and skirt the specific App Store guideline about blocking native features behind a paywall, since they likely don’t use Apple’s player, but in the browser? That’s stupid. I really hope this is a bug. YouTube’s app has gotten crazy with the length and frequency of ads and the insanely annoying prompts for a free trial of YouTube Premium when I no longer qualify for it. It has also been incredibly buggy. That’s part of the reason it was easier for me to switch to the browser. 90% of the time, my main feed would only load like 6 videos and then it wouldn’t load anymore as I continued scrolling.
Edit: looks like it still works on the iPad, but not on the iPhone. Maybe it is a bug...