I'm a software engineer but not very savvy on linux systems. I read this link and your approach seems fine https://linuxconfig.org/how-to-create-systemd-service-unit-in-linux
I know that rc.local is kinda deprecated and not supported on all distros but the solution is hacky anyways.
Messed...
I have the same issue on Ubuntu 20.04 installed on a Vivobook laptop. I believe it started after an update but I don't know exactly which one.
Thank you for the service start hack, my previous fix was to add the "acpi_backlight=vendor" to grub and setting a fixed brightness value at startup by...