QDockWidgetGroupWindow effectively sets new dockarea permissions on qdockwidget

if we have two qdockwidget with all qdockwidget features set, and each qdockwidget has its own setAllowedAreas. If you undock one dockwidget and then undock another one. It loses its designated allowed area which was set in the beginning.

Attached example can be used to reproduce, Screen recording shows steps how it can be seen.

reproduction steps are also mentioned here:

see here: https://forum.qt.io/topic/134181/qdockwidgetgroupwindow-effectively-sets-new-dockarea-permissions-on-qdockwidget