I checked out the ratio of the main frame on the embedded system, which is the same as on my desktop. The fixed pixel width and height of the main window are exactly the same.
The high dpi scaling attribute has no influence. Also switching from font.pixelSize to font.pointSize has the same unwanted effect.
How can the font proportions turn out different? If the main windows height is defined as 1080px, a font size of 20px must be clearly defined relative to it (1/54 of the main window height). But why does it take, let's say, 24px on my embedded system (which is 1/45)?
I can find many posts about scaling, but what I want is no automatic, random scaling at all.