[REG 5.15.2 -> 6.0.0] Cannot change style of quickcontrols2 gallery example using the menu

1. Run the quickcontrols2 gallery example.
   It's in Examples\Qt-6.0.0\quickcontrols2\gallery\gallery.pro of an installation.
2. Click the three-dot menu in the upper right corner.
3. Select "Settings" from the menu
4. Select a different style.
5. Click OK.
6. Restart the example.
   It still shows the same style.

Setting the style through

set QT_QUICK_CONTROLS_STYLE=Universal

on the command line works.