I’m not sure. Krita is a core18 snap and the problem is not observed there. Besides, core18 does not deliver libfontconfig*, it’s part of gnome platform snaps:
maciek@galeon:~ find /snap/gnome-3-2*-*/current/ -name '*fontco*.so*'
/snap/gnome-3-26-1604/current/usr/lib/x86_64-linux-gnu/libfontconfig.so.1
/snap/gnome-3-26-1604/current/usr/lib/x86_64-linux-gnu/libfontconfig.so.1.11.1
/snap/gnome-3-28-1804/current/usr/lib/x86_64-linux-gnu/libfontconfig.so.1
/snap/gnome-3-28-1804/current/usr/lib/x86_64-linux-gnu/libfontconfig.so.1.10.1
Krita comes with the same version of libfontconfig as gnome-3-26-1604 though:
maciek@galeon:~ find /snap/krita/current/ -name '*fontco*.so*'
/snap/krita/current/usr/lib/x86_64-linux-gnu/libfontconfig.so.1
/snap/krita/current/usr/lib/x86_64-linux-gnu/libfontconfig.so.1.10.1