Minimum backlight in Solus for AMD GPU is bright

Question

When I boot into Solus 4.0 with a live USB, the backlight can go extremely low, it even flickers slightly (flickers in backlight intensity, not on/off). I would describe it as 4 times dimmer than the minimum allowed brightness on Windows 10 and Solus 4.0 (partition on hdd; not live USB).

I was very happy that the live USB allowed such a dim backlight, since I used to have to change colour icc profiles on Windows at night to "simulate" dimness (just lowering contrast). "Now I can actually lower the hardware backlight!" I said to myself, this behaviour was also present when using an Ubuntu live USB a few years ago.

After installing Solus, I realized I couldn't lower the backlight as low as I could compared to the live USB, in fact it is the same minumum as in Windows. I did a lot of research and I now know that I am using amdgpu drivers (not pro) and not radeon drivers, my brightness range is from 0-255 (from /sys/class/backlight/amdgpu-bl0/brightness and max_brighness), manually changing the brightness text file to "0" in Solus partition does not achieve the extremely dim backlight intensity as experienced in the Solus live USB, and no decimal or negative numbers are allowed (invalid argument).

I even went back and booted from a Solus live USB and everything file-wise was the same as the partition as far as I could tell: amdgpu drivers and 0-255 backlight range, however, simply using small integers in the brightness file yielded significantly dimmer backlight than the Solus partition (as expected). I don't know how to check if the driver versions are the same, but based on this info, I'm asking if there's any way to "port" the backlight behaviour of the Solus live USB (or Ubuntu live USB for that matter) into my actual Solus partition.

I forget if the Ubuntu partition kept the extremely dim backlight as in the Ubuntu live USB, that was years ago and the partition has since been deleted.

About:

• GNOME: 3.28.2
• Processor: AMD A10-8700P ("Carrizo" APU)
• Graphics: AMD Radeon R6 Graphics (part of APU; no dedicated graphics)