Year is clipped when QDateEdit in a layout is in QGroupBox on Windows. This is shown in the pic1.
Way to reproduce the issue:
1) Create a new Qt Widget Application project with .ui file.
2. Open .ui file in Designer, place QGroupBox there and place the QDateEdit inside of QGroupBox. Then give the QGroupBox the focus and click a layout in the toolbar of the Designer.
Build and run the project with Qt 5.15. and clipping should be shown.
Or build and run the attached application with Qt 5.15.
Issue does not reproduce in Qt 5.9. branch nor on Linux.