QtQuick items flickering in Qt Wayland compositor

Some items in QtQuick UI intermittently fail to render when the application is run in a Qt Wayland compositor. This only occurs on embedded hardware, reproduced on a NXP i.MX8 QuadMax EVK, and the severity appears to be related to GPU load. Running the same application in Weston on the same hardware does NOT exhibit this behavior.

To reproduce the issue.

1. Run the attached example on minimal-qml Qt Wayland example compositor. You might need the run 2-3 instances of the client application.
2. You might need to click the the window to take focus and start rendering for the each instance.
3. Observe the last QML items are the ones that will disappear momentarily - watch the text showing "404", "403".