QSS Stylesheet with QWidget background-color hangs the application

We have quite a large style sheet for our application which works well.

Just for testing today we tried a stylesheet with the following content (no other styles were set):

QWidget {
    background-color: #fafafa;
} 

If we use that, the call to

gApplication->setStyleSheet(styleSheet);

will not return even after minutes. It keeps working in a function }}
static void updateObjects(const QList<const QObject *>& objects)
  Qt\6.5.3\Src\qtbase\src\widgets\styles\qstylesheetstyle.cpp

Is this a known problem? How can this be improved?