As someone else posted elsewhere in this thread, Asahi nets about 6.5 hours on a Macbook. Apples to apples the story is the same. It's really not that shocking. The effect of power management (or rather, when it's lacking) is very apparent when you do bare metal programming. The first thing you do when you finally get something booting is kill a battery in less than an hour with a while(true).

I think you may have misread that post. It said Linux was 5 hours, MacOS was 6.5 hours. There's a gap (Linux gets 77% the life of MacOS), but it's apparently not that significant.