When clearing a QMenu, actions are only removed, not deleted. Minimal example:

QMenu m_pMenuOwner = new QMenu("Menu owner");
QMenu m_pMenuOther = new QMenu("Menu other");
while (true) {
  for (quint64 j = 0; j < 10000; ++j) {
    auto* pAction = new QAction("Action", m_pMenuOwner);
    m_pMenuOwner->addAction(pAction);
    m_pMenuOther->addAction(pAction);
  }
  // without this line the actions get deallocated, with it they don't
  m_pMenuOwner->clear(); //
  m_pMenuOther->clear();
  m_pMenuOwner->clear();
}

I've attached the Qt Creator project and a gif with the memory consumption.