The monster laptop consumes more power because it has all of that RAM, the battery is sized to "not cause a crisis on an airplane if it burns up" not to power a machine of that type, particularly after a year of battery aging.

I have an Alienware that runs rings around any Mac and can do ML dev work with NVIDIA if it is on the plug but on battery I count on it to keep running as I move it to another plug and for the battery to maintain sleep mode for 48 hrs or so.