mouse cursor fragments appear in newly exposed window areas in QtQuick (on Windows)

When I resize QtQuick/QML window by dragging the window corner, some ugly mouse cursor fragments appear in the newly exposed areas. I am attaching a video and a screenshot. Needless to say that this does not look good. I have not seen it in any other framework so I assume this must be a bug in QtQuick.

The video is very quick so the unwanted effect is hard to see. But it is clearly visible in the screenshot (I circled it in red).

PS: Also resizing of window feels much slower, lagging behind the mouse cursor movement, and more "stutterring" than in other GPU accelerated frameworks, e.g. Flutter.