QPainter does not honor devicePixelRatio in drawTiledPixmap

I am using QT_SCALE_FACTOR=2 to simulate a high DPI environment.

By default, all pixmaps are scaled up by a factor two. According to the documentation, it should be possible to draw images and pixmaps at their 'native' size (one image pixel == one screen pixel) by calling setDevicePixelRatio with the devicePixelRatio of the widget. This does indeed work for drawPixmap, but not for drawTiledPixmap - in that case setDevicePixelRatio seems to have no effect whatsoever.

Repeating the test with QT_SCREEN_SCALE_FACTORS instead of QT_SCALE_FACTOR produces the same result. Qt::AA_UseHighDpiPixmaps doesn't make any difference, it only changes the appearance of icons (from QIcon).

Am I missing something?