Currently X and Xwayland (unless set otherwise) defaults to a DPI of 96.
GTK on wayland (unless set otherwise) defaults to a DPI of 96.
Qt (currently) defaults to physical size/resolution. This leads to
reports that Wayland looks big.
Qt is potentially also changing to 96 for > Qt5.10.
(it's in review at the time of writing)
Now kwin has proper scaling support, legacy apps get scaled by the
compositor without font hacks, and apps that scale themselves need a
non-scaled font DPI. (i.e a 4k screen at 2x still wants a DPI of 96 not
We want to change the wayland scale factor not the font.
If a user does override this setting that override will still work.