C++ class wizard autocomplete widget misplaced, crashing in Qt6.9/Wayland

The "New File -> C++ Class" Wizard shows autocompletion for the "Class name" and "Base class" input.

This widget is incorrectly placed in the center of the screen in Qt6.8.2/Wayland. (see attached image)

QtCreator closes when compiled with Qt6.9.0/Wayland. With WAYLAND_DEBUG=1, the last shown messages are:

[...] {Display Queue} wl_display#1.error(xdg_surface#66, 0, "wl_surface@55 already has a different role")
The Wayland connection experienced a fatal error: Protokollfehler

QtCreator works without apparent issues when using X11. (QT_QPA_PLATFORM=xcb environment)