kde-gtk-config creates empty strings for gtk-theme
kde-gtk-config does not default on breeze and creates empty strings for gtk-theme inside gtk config files it creates. Tested this on archlinux without any customizations. Strange thing is that if i install the complete kde-applications group it does work to use breeze by default without the need to set this manually. But installing kde-gtk-config itself seems to miss a dependency, could be archlinux packaging issue too... but i do not see missing dependency from what i checked on the source of it. And i checked https://community.kde.org/Distributions/Packaging_Recommendations to have all needed packages installed. Question is may more general about what exactly is needed to set default in GTK theme settings? This was working before on plasma 5 indeed. Feel free to shout at me if this is the wrong place.