Italic rotated text on Linux renders incorrectly

Italic rotated text on Linux often paints incorrectly. The letters seem to be displaced horizontally rather than made italic. This seems to be connected with a QPainter which has a scaling applied. It seems to work ok on some fonts, but not others, even if they provide an italic or oblique version.

Please see example program and screenshot below (Ubuntu 21.04 Hirsute).