screen brightness not working after update (solved)

backlight slider stopped working on my amd ryzen 2500u laptop, KDE was using a fallback option with dimming the image(this was bad) without any error messages(not even in dmesg or when using light command that affected nothing)

I had to remove acpi_backlight entries with grubby to make it work again

you check like this: sudo grubby --info=ALL | grep args

then if you see acpi_backlight(for instance acpi_backlight=native, or =vendor) you can run

sudo grubby --update-kernel=ALL --remove-args="acpi_backlight=native"

(replace ALL with the one you want to change if you don't want to change every kernel args)

more info here https://hansdegoede.livejournal.com/26427.html

it happened to me on fedora 41 recently so I guess it makes sense to post this to make it easier for others to google the solution