Power Management - Hybrid Sleep & Battery Critically Low action

 * Cinnamon 4.8.6
 * Mint 20.1 (same problem was at least with Mint 20.0, dunno about earlier versions, I'm a new linux user)
 * Nvidia RTX 2060 Mobile, 450.119.03-0ubuntu0.20.04.1
 * 64 bit

Issue

If the Enable Hybrid Sleep switch is off in the Power Management settings, system still does HybridSleep when Battery is critically low action kicks in, even if Hibernate is selected as the action type.

Here's my power settings (the "suspend inactive on a/c" box is empty because I have set custom timeout (and type) with dconf, see the bottom left of the image of those settings):

And screenshot from journalctl when system tries to do HybridSleep:

/etc/UPower/UPower.conf file has this section:

# The action to take when "TimeAction" or "PercentageAction" above has been
# reached for the batteries (UPS or laptop batteries) supplying the computer
#
# Possible values are:
# PowerOff
# Hibernate
# HybridSleep
#
# If HybridSleep isn't available, Hibernate will be used
# If Hibernate isn't available, PowerOff will be used
CriticalPowerAction=HybridSleep

If that CriticalPowerAction is changed to Hibernate, the system does hibernate, not HybridSleep.

My laptop always locks up if the system tries to do HybridSleep. I don't understand why. Suspend alone works, and hibernate alone works too, but not HybridSleep.

Is the /etc/UPower/UPower.conf file safe from anything changing it, like some system/package update resetting/updating it? Something like /etc/UPower/UPower.conf.d/10-upower.conf doesn't seem to exist?

Interestingly the /etc/UPower/UPower.conf file starts with this comment:

# Only the system vendor should modify this file, ordinary users
# should not have to change anything.

Here's a wish that the user wouldn't have to edit that file, nor use dconf, i.e. I hope that the Power Management GUI settings would have all the settings (e.g. Time/PercentageLow/Critical/Action et al. settings).

Start by reviewing the Power Management settings shown in the issue, /etc/UPower/UPower.conf, and the journalctl output for the critical-battery action. Trace how the GUI and dconf settings relate to UPower's CriticalPowerAction. Done means the configured critical-battery action is honored without requiring manual edits to the system configuration.