Qt5 QMenu will get hidden instantly after showing when running with QT_QPA_PLATFORM=xcb under XWayland

Affected version

• Fedora 38
• Mutter 44.3
• Issue does not appear under Xorg or when starting application with `QT_QPA_PLATFORM=wayland`
• Qt 5.15.10

Bug summary

When running a Qt App with the `QT_QPA_PLATFORM` environment variable set to `xcb` QMenus sometimes get closed "instantly" after showing. This results in context menus being unusable in the application.

Steps to reproduce

This can be seen in Mixxx: https://github.com/mixxxdj/mixxx/issues/11576
Alternatively it's also trivially reproduced in a demo application (see demo.zip )

Right-clicking the "rightclick me" label will only flash the qmenu since its being hidden so shortly afterwards again (can be seen by setting a breakpoint in `QMenu::hideEvent`).
A similar issue can be seen when using the Menubar QMenu, sometimes staying closed after a click.

What happened

The Menu randomly doesn't not show up. As debugging reveals, because its hidden shortly after spawning it.

What did you expect to happen

The menu should've shown up on every click.

Relevant logs, screenshots, screencasts etc.

The xcb recording shows the faulty behavior while the wayland recording shows the correct one.
xcb.webm
wayland.webm