I use Fedora 44 KDE edition with the nouveau driver and cannot adjust brightness at all, and given that I had this problem previously on linux mint 21.3 and solved it back then by adding the “acpi_backlight=vendor” parameter, I tried to use this same solution on Fedora 44, but then when I rebooted, the brightness slider disappeared! I hope someone could help me fix this problem.
Nevermind, this amazing site just recommended me a post of another user who had the same problem and the solution on that post worked.
Simply run this command:
sudo grubby --args="acpi_backlight=native" --update-kernel=ALL