Latest update on my MacBook Late 2008 - Brightness keys no longer functional

I ran the eso-update to make the OS up-to-date on a MacBook Late 2008 I’m planning on selling and all of a sudden, the brightness keys aren’t doing their job at all. The rest work fine without issues and on my ASUS X54C with the latest updates, it works fine on it.

I have the hid_apple.fnmode=2 parameters set in the kernel conf files under /efi/loader/entries since I didn’t want to press Fn+Alt+F4 to close an application. The brightness controls worked beforehand and this was all of a sudden. The latest kernel is 6.7.2-arch1-2, whereas the previous was 6.7.1-arch1-2 (this one had working brightness controls).

Is there a patch for this somewhere? It uses an nVidia GeForce 9400M GPU and a C2D 2.0GHz CPU.