Adjust screen brightness issue (Lenovo Laptop, NVIDIA, XFCE) – Manjaro/Arch Linux

i915.enable_dpcd_backlight=0 Boot parameter. In the file /etc/default/grub add that previous code into the quotation marks after GRUB_CMDLINE_LINUX_DEFAULT=“”

Verify to grub file:

[lnx@lnx ~]$ grep "GRUB_CMDLINE_LINUX=" /etc/default/grub
GRUB_CMDLINE_LINUX="i915.enable_dpcd_backlight=0"

Update to grub:

sudo update-grub