QQuickWidget object stay in QML Engine cache after deletion

We have an QQuickWidget class, which its object sometimes could be created and deleted dynamically pretty frequently - Menus and popups for example.

Its source is set to a qml file at construction.

class MyWidget: public QQuickWidget {
  MyWidget::MyWidget(QQmlEngine* engine) : QQuickWidget(engine, nullptr)
  { 
    setSource(QUrl("qrc:/qml/components/myMenu.qml")); 
    ...... 
  }
  ......
}

 
We noticed that the memory usage has slightly increasing trend overtime by repeatedly create MyWidget,

After checking, this memory issue is from setSource - Looks like after an object is deleted, it's not cleared from QML engine and still stay in some caches?

Reproduce ;

1. Start any memory tool (in-code memory usage record like psutil, or external analysis valgrind, heob)
2. Construct any QQuickWidget with setSource call
3. Delete the object after 3~5 seconds (the time doesn't really matter)
4. Repeat step 2 and 3 in a loop for a significant amount of time, like ~5 hours.

Expected :

• Memory consumption not increasing, stay at a flat level.

Actual:

• Memory consumption has minor increasing trend
  
• From heap analysis, that increasing is due to allocation by setSource call.

Note:

• After some workaround by simply avoid repeatedly creating/deleting QQuickWidget , memory consumption no longer increase.