/etc/fonts/conf.d/90-fonts-baekmuk.conf is in fonts-baekmuk 2.2-11.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/fontconfig/conf.avail/90-fonts-baekmuk.conf
/usr/share/fontconfig/conf.avail/90-fonts-baekmuk.conf