I need to go back and watch the marketing material, but I think everytime they brough up battery life, it was under conditions. Like 20 hour battery life browsing the web. 18 hour battery life with video playback. I don't think anywhere they claimed 20 hour battery life using something like Blender.

Which of course should be expected. My M1 probably gets about 18-20 hours when I am just web browsing. If I am compiling Xcode projects, half that. Messing around in C in Emacs, probably 14-16 hours battery life.