services.xserver.logFile

Controls the file Xorg logs to.

The default of /dev/null is set so that systemd services (like displayManagers) only log to the journal and don't create their own log files.

Setting this to null will not pass the -logfile argument to Xorg which allows it to log to its default logfile locations instead (see man Xorg). You probably only want this behaviour when running Xorg manually (e.g. via startx).