QScrollArea scrollbars disappear when you make the window bigger than the available desktop space twice

When you resize a window to a size bigger than the available desktop space the window will resize itself to the available desktop space and the scroll area inside will adjust itself.

If the widget inside the scroll area is still bigger than the available space, the scrollbars will remain visible (correct)

However, if you perform a second resize, the scroll bars will disappear. Sometimes only one scrollbar disappears, sometime both. The window itself will not change size (the minimize, maximize and close buttons do not change their positions).

I create an application based on the imageviewer example. I simply changed the paste implementation so I can trigger the issue by pressing CTRL+V twice.

void ImageViewer paste()
{
    imageLabel->setFixedSize(QGuiApplication::primaryScreen()->availableSize().width()+300, QGuiApplication::primaryScreen()->availableSize().height()+300);
    resize (imageLabel->size());
}

Then I run the program, load an image (any will do) and press CTRL+V once.

Then I manually move the window near to the (0, 0) position (carefully so I don't trigger the maximize). This will show that the window is the size of the desktop and has scroll bars.

Once I press CTRL-V again the scroll bars will disappear.

I'm attaching two images (one with the scroll bars, the other without) and also the app I used to reproduce it (image viewer example with paste changed to resize the window)