Right, and that is the issue. If I buy a Mac and run MacOS I can be sure that I get long battery life. If I get a PC laptop and run Linux, it's a random crapshoot if the random combination of hardware, kernel version, etc. (I also used Silverblue and Fedora) of whether you get a good battery life.

Maybe Asahi Linux will improve things, since they only target a very small number of hardware configurations.