Brightness settings do not work [lxqt] [arch] [Lenovo 500e]

I have recently installed arch on my old Lenovo 500e Chromebook so that I could keep doing school work on it. everything is working great except the brightness settings. I chose lxqt to be my DE because of how light weight it is but the built in “brightness” app cannot change my brightness. in the app there are two sliders “backlight” and “eDP-1”. changing the “eDP-1” setting kind of makes it darker but there it a weird haze that ends up making still very bright in low light areas. there are also these HUGE dithering artifacts that look very bad and make images/videos look blurry. making it brighter causes it to look washed out. the “backlight” setting it set to the lowest by default and changing it does nothing. I feel like instead of lowering the power going to the screen to naturally lower the brightness it is digitally clamping the brightness.

I don’t have your exact chromebook but a similar 11.6inch with an N3450 cpu,so your mileage may wary, but had the same problem. Found that there’s been a regression in the newer kernel versions, and the screen no longer worked correctly, no brightness control + it would not power on the screen from sleep.
Change kernel to version 5.10 or 5.15 and see if it fixes the problem, it did on my chromebook.
I haven’t had the time to, but from that point you can try newer and newer kernels and see what version broke the display driver. Also maybe try the newest unstable kernel, maybe just maybe someone reported the regression lately and it was fixed.

I do not recommend this. Anything older than 6.4 is not supported (as per the documentation)

From what I remember downgrading the kernel from 6.9 to 6.6 did not fix the issue, going from that to 5.x(5.15, I think but not 100%) did. Didn’t try any kernel in between, so maybe the issue started after 6.4

I am apprehensive about downgrading my kernel because I fear it might mess with my apps/drivers.

Installing Ultramarine Linux and updating the kernel fixed any issues I had with the display and sleep/resume on my apollo lake chromebook REEF

I installed the “flagship edition” but probably all of them would work.

ok so here’s something weird.
I bricked my installation and had to reinstall everything. I did not do anything different but when I booted up and tried to change my brightness it just worked. I do not know what changed but I am happy it did.