QHostInfo weird behavior with functor

#include <QCoreApplication>
#include <QDebug>
#include <QtNetwork>

class Receiver : public QObject
{
  Q_OBJECT

  int dummy = 43;

public:

  Receiver(QObject *parent = nullptr) : QObject(parent) { qDebug() << "CTR" << this; }
  ~Receiver() { qDebug() << "DTR" << this; }

public slots:

  void received(const QHostInfo &info)
  {
    // this will be called from network thread when
    // invoked via "mordern connect syntax" but
    // from the main ui thread when using the "old connect syntax"
    qDebug() << "Result" << info.addresses() << dummy;
  }
};

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  {
    Receiver r;
    // crashes, because member is invoked directly via QSlotObjectBase:call
    QHostInfo::lookupHost("www.spiegel.de", &r, &Receiver::received);
  }

  {
    // safe, handled by queued signal dispatching
    Receiver r;
    QHostInfo::lookupHost("www.zeit.de", &r, SLOT(received(QHostInfo)));
  }

  return a.exec();
}

#include "main.moc"