Google has resolved the issue with iOS 14 and the YouTube video service. Now on the YouTube mobile site, the Picture-in-Picture feature has started to work correctly, even without a paid subscription.
Apple released a new version of its mobile operating system iOS 14 for the iPhone on September 16. One of the innovations is the Picture-in-picture (PiP) function. However, with the YouTube site, the innovation worked for users of the paid YouTube Premium subscription, and without a paid subscription, users complained about the PiP function being blocked.
YouTube for web now works correctly with Safari on iPhone in Picture-in-Picture mode without having to pay for YouTube Premium.
Google has not announced anything on this matter, however users confirm that the problem is gone.