https://wccftech.com/finally-youtube-picture-in-picture-is-coming-for-all-ios-users-in-the-u-s/

YouTube is finally gearing up and officially announcing picture-in-picture support for all iOS devices. The upcoming support will allow everyone to close the YouTube app and continue watching their videos in a smaller pop-up window. Apple rolled out support for picture-in-picture last year and while many third-party apps have integrated the feature into their apps, YouTube was a bit indecisive. However, YouTube for iOS is now officially gaining picture-in-picture support for users in the United States.

As mentioned earlier YouTube will be gaining support for picture-in-picture or PiP mode in the United States. At this point in time, the company will be rolling out picture-in-picture support for all premium subscribers of the service (via MacRumors). However, a larger rollout will take place soon which will be available to all and not just the premium subscribers. It was previously speculated that the feature will only be available for premium subscribers, but it seems this is not the case.