I observed this same issue, and checked ~/.config/fontconfig/ on a hunch. It turned out I had an autogenerated (from lxqt-config appearance, apparently) fonts.conf there, which forced 96 DPI like so:
<match target="pattern">
<edit name="dpi" mode="assign">
<double>96</double>
</edit>
</match>
Commenting out this block (or simply removing the offending file, I
didn't want it there!) restored correct behavior for me.
--
Peter Piwowarski <[email protected]>
