Random Brightness UP and down .
systemd-backlight@backlight:acpi_video0.service loaded failed failed Load/Save Screen Backlight Brightness of backlight:acpi_video0
systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0
Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
Active: failed (Result: exit-code) since Sat 2021-11-27 23:36:07 IST; 19min ago
Docs: man:systemd-backlight@.service(8)
Process: 785 ExecStart=/usr/lib/systemd/systemd-backlight load backlight:acpi_video0 (code=exited, status=1/FAILURE)
Main PID: 785 (code=exited, status=1/FAILURE)
CPU: 3ms
Nov 27 23:36:07 Linux systemd[1]: Starting Load/Save Screen Backlight Brightness of backlight:acpi_video0…
Nov 27 23:36:07 Linux systemd-backlight[785]: Failed to get backlight or LED device ‘backlight:acpi_video0’: No such device
Nov 27 23:36:07 Linux systemd[1]: systemd-backlight@backlight:acpi_video0.service: Main process exited, code=exited, status=1/FAILURE
Nov 27 23:36:07 Linux systemd[1]: systemd-backlight@backlight:acpi_video0.service: Failed with result ‘exit-code’.
Nov 27 23:36:07 Linux systemd[1]: Failed to start Load/Save Screen Backlight Brightness of backlight:acpi_video0.