When using QtMultimedia.VideoOutput and Qt3D.Scene3D at the same time, VideoOutput can't bringt its frames to the screen when running on Android. No problems on macOS and iOS.

I attached an example where I load an empty Scene3D using a Loader to toggle it's existence.

In the video you see a constant feed of an Android device's camera which stops rendering when Scene3D gets loaded. If using a MediaPlayer with sound, you can still hear the sound while rendering stops. Unloading Scene3D gets back the video feed.