QPainter coordinates rounding broken when HiDPI scaling is used

QPainter coordinates rounding is broken in in Qt6 when HiDPI scaling is enabled and set to the "typical" value of 125%. The 1px offsets are clearly visible on the attached GPXSee screenshot (Linux/X11, but the same applies to Windows 11).

The issue affects only the raster renderer, when a QOpenGLWidget is used as the viewport instead of the standard QWidget (select "Use OpenGL" in the "System" preferences of GPXSee), the rounding error vanishes.