Interactive Flickable with pressDelay makes childMouseEventFilter to lose MouseButtonPress event

Our commercial customer has a sidebar in a mobile application which uses an overlay with QQuickItem::childMouseEventFilter for detecting when a Flickable based vertical sidebar is dragged open or closed horizontally. Closing the sidebar is not working anymore on Android and iOS after porting from Qt5.15 to Qt6.5. I wrote a test app to demonstrate the issue.

When tapping the view, it shows that childMouseEventFilter is not receiving MouseButtonPress when Flickable is interactive and its pressDelay property is set to some value. Only MouseButtonRelease (and MouseMove events if finger moves) is received.

Find attached a demo app named flickablechildeventtest and a text file flickablechildeventtest_results.txt containing a log output from the app on macOS, iOS and Android on both Qt6.5.2 and Qt5.15.9. You can see in the log output that MouseButtonPress events are not received in childMouseEventFilter on iOS and Android on Qt6.5.2 when the mentioned Flickable.pressDelay property is given a value.