Debian 12 / Gnome / How to shutdown laptop after battery percentage crossed

Hello Linux community,

I need some help with shutting down my laptop when the battery reaches a low percentage.

I am using Debian 12 with the GNOME desktop. WARNING: Minimal installation with self selected packages.

What I want to achieve is, that the laptop just does a 'halt -p' or shuts itself down when the battery is below 20%.

What I did so far:

• Look into GNOME settings in the power settings area and I found nothing helpful
• I edited /etc/Upower/UPower.conf with my settings and changed the CriticalPowerAction to PowerOff, ensured the upower daemon is running via systemctl status and rebooted. The result was that I get a warning popup message in GNOME when the battery load reaches 21%, but it does not shutdown the laptop at 20% or under 20%, although I get another pop up announcing that the laptop would be shutdown
• I ensured laptop-mode-tools and gnome-power-manager settings are installed

Any help/pointers for further help would be highly appreciated.