Sometimes, when minimizing the video player while watching a video, the player closes instead of going into PIP.
We've seen that happen as well and haven't been able to identify what circumstances make it work or not. We don't have any control over this happening — we request that PIP should happen when the app goes into the background and the OS is responsible for doing it. Usually it works, sometimes it doesn't.
Something to note regarding this issue. I tend to watch a lot of YouTube videos via Channels on iOS/iPadOS and have noticed that when playing a,video in a vertical orientation, it sometimes confuses the Channels player and after switching back to playing a horizontal video, the player keeps the wrong aspect ratio when in PIP. Not sure if this could be related…