Picture and picture doesn’t work for iOS 14 and iOS 15, when app goes into background

Currently our iOS app has implemented the picture&picture functionality according to this documentation.

We realise that when our app goes into background, picture&picture is not displayed on the main screen for iOS 14 and iOS 15.

This behaviour doesn’t occur for iOS16 and iOS17. In that iOS version, picture&picture floating window appears.

Which Client iOS SDK version?

To Reproduce
We follow the next steps to reproduce the behaviour for iOS 14 and iOS15:
Integrate Zoom iOS Client SDK into our app
From our app, using a iPhone 6, we join a zoom meeting hosted by another person on zoom desktop client.
We minize our app while we’re in the meeting.
Picture&picture floating window doesn’t appear.

Any suggestions on how to solve our problem? Thanks

iPhone6 - iOS 15
iPhoneSE - iOS 14