Comment 28 for bug 1861925

I have Lenovo Legion 5 15ARH05 with Ryzen 5 4600H. I've checked that the issue is present in Ubuntu 20.10 beta, Fedora 32 with Kernel 5.8, Fedora 33, Manjaro with latest 5.8 kernel, opensuse tumbleweed.
On manjaro and fedora 32 with any kernel 5.6, and MX Linux backlight can be changed at first. But it seems force shutting down the laptop (hold power button) immediately breaks it and upon the next boot brightness cannot be changed. I've reproduced this behavior in manjaro, fedora 32, and MX Linux all with kernel 5.6.*.