A bit of a sidenote:

PopOS came installed on my system76 laptop. But that's not important here.

What intrigues me more is that the laptop had terrible battery life. And I mean terrible by even 2010 standards. And I bought it in 2018. It would last less than an hour on average, and less than 40 minutes if I was doing something demanding.

I use past term "had" as although I am still using this laptop today, somehow after 3 years, it's battery life has just increased dramatically and completely out of the blue.

Somehow I can now use it for over three hours while running off battery life. I've been pretty confused as to how this has happened, and am now wondering if anyone with a system76 might have experienced something similar.

I'm really hoping it will go up to nine hours by 2024. It's a great laptop.

Have you tried using TLP? https://linrunner.de/tlp/

There is also "Auto CPUfreq", but I have not tried it yet. Automatic CPU speed & power optimizer for Linux: https://github.com/AdnanHodzic/auto-cpufreq