/etc/fonts/conf.avail/ is in fonts-dejavu-core 2.34-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/etc/fonts/conf.avail/20-unhint-small-dejavu-lgc-sans-mono.conf
/etc/fonts/conf.avail/20-unhint-small-dejavu-lgc-sans.conf
/etc/fonts/conf.avail/20-unhint-small-dejavu-lgc-serif.conf
/etc/fonts/conf.avail/20-unhint-small-dejavu-sans-mono.conf
/etc/fonts/conf.avail/20-unhint-small-dejavu-sans.conf
/etc/fonts/conf.avail/20-unhint-small-dejavu-serif.conf
/etc/fonts/conf.avail/57-dejavu-sans-mono.conf
/etc/fonts/conf.avail/57-dejavu-sans.conf
/etc/fonts/conf.avail/57-dejavu-serif.conf
/etc/fonts/conf.avail/58-dejavu-lgc-sans-mono.conf
/etc/fonts/conf.avail/58-dejavu-lgc-sans.conf
/etc/fonts/conf.avail/58-dejavu-lgc-serif.conf