QImage::scaled does not keep format from original to scaled image

void MainWindow::testQImageScaled(){
    QImage img (50, 50, QImage::Format_ARGB32);
    Q_ASSERT (img.format() == QImage::Format_ARGB32);
    img.fill(Qt::red);
    Q_ASSERT (img.format() == QImage::Format_ARGB32);
    QImage imgScaled = img.scaled(100, 100, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
    Q_ASSERT (img.format() == QImage::Format_ARGB32);
    if (imgScaled.format() == QImage::Format_ARGB32_Premultiplied)
        qDebug()<<"Format was implicitly changed from ARGB32 to ARGB32_Premultiplied with no notes in documentation about this.";
    Q_ASSERT (imgScaled.format() == QImage::Format_ARGB32);
}