systemd-backlight@.service, systemd-backlight — Load and save the display backlight brightness at boot and shutdown
systemd-backlight@.service
/usr/lib/systemd/systemd-backlight
systemd-backlight@.service
                is a service that restores the display backlight
                brightness at early boot and saves it at shutdown. On
                disk, the backlight brightness is stored in
                /var/lib/systemd/backlight/.