Comment 2 for bug 1938195

Judging by the top of the config file it sounds like the Nvidia driver writing and overwriting it. There was an update to nvidia-graphics-drivers-460 on 21 July.

In theory this is what /usr/share/X11/xorg.conf.d/ is for, to add custom configs that other packages won't touch. But I don't know if spreading the nvidia config across multiple files with potentially duplicate sections would work.