By default, with DirectWrite as the fontengine, when not using high-DPI scaling, fonts will render with CLEARTYPE_GDI_CLASSIC, which can make them look squashed (e.g. no space between m and e):

fontenegine	DirectWrite	GDI
top: default hinting bottom: vertical hinting

_{(code in hinting-1.cpp)}

I tested this in a larger application and this does make quite the difference (also having to manually set the hinting doesn't seem like a good solution, especially since DirectWrite is the default). If you enable high-DPI scaling, the default hinting will look like with GDI again.

Removing the check for high-DPI scaling in hintingPreferenceToRenderingMode (qwindowsfontenginedirectwrite.cpp) would resolve this issue.