QVariant is loosing meta type when passed from C++ to QML and back

When you create a QVariant in C++ and fill it with a custom enum (which is properly registered with Q_ENUM), then pass that QVariant to QML, store it in QML in a property of type 'var' and then invoking a C++ method from QML and passing along that var property, the QVariant parameter of that C++ method has suddenly a metaType 'int'.

This is a regression in Qt6, worked fine in Qt 5.15.

A testcase that shows the scenario is attached.