Comment by okanat

Newer laptops come with extra power peripherals and sensors. Some of them are in ACPI tables, some are not. Most of them are proprietary ASICs (or custom chips, nuvoton produces quite a bit of those). Linux kernel or the userspace has poor support for those. Kernel PCIe drivers require some tuning. USB stack is kind of shaky and power management features are often turned off since they get unstable as hell.

If you have a dGPU, Linux implementation of the power management or offloading actually consumes more power than Windows due to bad architectural design. Here is a talk from XDC2025 that plans to fix some of the issues: https://indico.freedesktop.org/event/10/contributions/425/

Desktop usage is a third class citizen under Linux (servers first, embedded a distant second). Phones have good battery life since SoC and ODM engineers spend months to tune them and they have first party proprietary drivers. None of the laptop ODMs do such work to support Linux. Even their Windows tooling is arcane.

Unless the users get drivers all the minute PMICs and sensors, you'll never get the battery life you can get from a clean Windows install with all the drivers. MS and especially OEMs shoot themselves in the foot by filling the base OS with so much bloat that Linux actually ends up looking better compared to stock OEM installs.