The ~ / .fonts.conf file must be moved. Programs that still read it there cause the following warning:
Fontconfig warning: “/etc/fonts/conf.d/50-user.conf”, line 9: reading configurations from ~/.fonts.conf is deprecated.
To remove it, we can:mkdir ~/.config/fontconfig; mv ~/.fonts.conf ~/.config/fontconfig/fonts.conf
But programs that have not yet been updated can recreate it.