QToolBar::clear() leaks memory

......
class MainWindow : public QMainWindow
......

public slots:
    void refresh_toolbar();
private: 
    QToolBar *tb;
......

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    tb = new QToolBar(this);
    addToolBar(tb);

    refresh_toolbar();
}

void MainWindow::refresh_toolbar()
{
    static int gg = 0;
    QList<QAction*> acts = tb->actions();

    tb->clear(); // Here actions's memory is not released!

    // This should release those actions and free the memory,
    // Qt-5.9.9-mingw32 does that OK,
    // Qt-5.12.9-msvc2019 and Qt-5.15.1-msvc2019 leaks memory
    foreach (QAction* act, acts) {
        delete act;
    }

    for(int i = 0; i < 150; ++i)
    {
        int title = gg * 1000 + i;
        QAction *action = tb->addAction(QString::number(title));
        action->setData(i);
        action->setCheckable( true );
        action->setChecked( title % 3 );
    }

    if(gg < 1000)
        QTimer::singleShot(gg++ ? 10 : 5000, this, SLOT(refresh_toolbar()));
}
...