QQuickPaintedItem directly used, will grow infinite memory

I have a class PaintedItem that inherits QQuickPaintedItem, when I using in qml,
then keep changing the window size，memory will always grow.

For example, have a class:

class PaintedItem : public QQuickPaintedItem
{
   PaintedItem(QQuickItem *parent = nullptr) : QQuickPaintedItem(parent) { }
   void paint(QPainter *painter) 
   {
      //do nothing
   }
}

After register in qml:

Window{
   visible: true
   width: 640
   height: 480
   PaintedItem {
     anchors.fill: parent
   }
}

Then, constantly changing the size of the window, the memory will grow indefinitely. 

Qt version is 5.13, but 5.12 is no problem.