QQuickView does not expand with QWidget::createWindowContainer()

I attached screenshot for better understanding.

I colored every background of the QDialog to show the problem more specific.

It is a simple QDialog with QPushButtons and a QQuickView which shows the QML VideoOutput.

In the top left corner is the QML VideoOutput, behind this there is a blue background.

The blue background is the complete QML/QQuickView.

The black rectangle seems to be the window created from the QWidget::createWindowContainer() function.

From my understanding and this is also what I want is that the QML VideoOutput or the QQuickView will as big as the black background

This effect only occurs on android, on Windows or Linux it seems to work

I also tried QQuickWidget as an alternative, but with this approach the the complete dialog was not shown