arcsin(x)

System76's Lemur Pro

Battery Charge Thresholds

The default 90-100 charge thresholds seem to quickly destroy the battery (causing it to swell greatly).

see https://support.system76.com/articles/laptop-battery-thresholds/

set below 60-80?

Backlight

After installing Xubuntu 22.04 LTS and system76's ppa, the following issue occured:

When the screen turned on again after blanking, the backlight would come on at 100% brightness despite its setting before blanking.

A discrepancy would then exist between /sys/class/backlight/intel_backlight/actual_brightness and /sys/class/backlight/intel_backlight/brightness.

The fix was to modify the file /etc/defaults/grub to change 

  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
to 
  GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=native"
and regenerate the grub install.

"acpi_backlight=vendor" as sometimes mentioned didn't work on this kernel, and removed the /sys/backlight directory.