Disabled widgets are not greyed out

In the attached project, the second menu item is disabled. Still, both first and second item are displayed with the same style, i.e. the second item is not greyed out. This is very confusing for the user.

The same thing happens with the two `QCheckBox`es.

Tested with Qt 6.7.2 on Linux, both release and debug builds.

Edit:
This issue has already been reported here: https://bugreports.qt.io/browse/QTBUG-122715
Some discussion on the issue here: https://forum.qt.io/topic/157584/disabled-menu-item-not-greyed-out