how to solve QGraphicsscene memory leak

[H_AND_K]

Hi, I have a question for you. Use the official Demo Chip example

Set setItemIndexMethod(QGraphicsScene::NoIndex) in QGraphicsScene; And set shortcuts to add and remove QGraphicsItem, but found that memory kept growing.
Please look at my code:

MainWindow::MainWindow(QWidget *parent)
   : QWidget(parent), scene(new QGraphicsScene(this))
   , h1Splitter(new QSplitter(this)), h2Splitter(new QSplitter(this))
{
   scene->setItemIndexMethod(QGraphicsScene::NoIndex);
   populateScene();

   QSplitter *vSplitter = new QSplitter;
   vSplitter->setOrientation(Qt::Vertical);
   vSplitter->addWidget(h1Splitter);
   vSplitter->addWidget(h2Splitter);

   View *view = new View("Top left view");
   view->view()->setScene(scene);
   h1Splitter->addWidget(view);

   view = new View("Top right view");
   view->view()->setScene(scene);
   h1Splitter->addWidget(view);

   view = new View("Bottom left view");
   view->view()->setScene(scene);
   h2Splitter->addWidget(view);

   view = new View("Bottom right view");
   view->view()->setScene(scene);
   h2Splitter->addWidget(view);

   QHBoxLayout *layout = new QHBoxLayout;
   layout->addWidget(vSplitter);
   setLayout(layout);

   setWindowTitle(tr("Chip Example"));
}

void MainWindow::keyPressEvent(QKeyEvent *event)
{
   if(event->key() == Qt::Key_D && event->modifiers()== Qt::CTRL)
   {
       scene->clear();
   }
   if(event->key() == Qt::Key_N && event->modifiers()== Qt::CTRL)
   {
       populateScene();
   }
}

void MainWindow::populateScene()
{
   QImage image(":/qt4logo.png");
   scene->clear();
   qInfo()<<"item size:" << scene->items().size();
   // Populate scene
   int xx = 0;
   int nitems = 0;
   for (int i = -11000; i < 11000; i += 110) {
       ++xx;
       int yy = 0;
       for (int j = -7000; j < 5000; j += 70) {
           ++yy;
           qreal x = (i + 11000) / 22000.0;
           qreal y = (j + 7000) / 14000.0;

           QColor color(image.pixel(int(image.width() * x), int(image.height() * y)));
           QGraphicsItem *item = new Chip(color, xx, yy);
           item->setPos(QPointF(i, j));
           scene->addItem(item);

          ++nitems;
      }
   }
}

[H_AND_K]

We used the Qt 5.15.2 MSVC compiler and tested the demo with the keystroke Sprite and found memory growth.