I have been seeing this in video reviews of the Mac Studio and here at 9to5 Mac by Ben Lovejoy. Basically this is true for these power levels, but the NVIDIA card they are comparing too can go much higher on wattage, and thus is much more powerful, and the new 2090 Ti can up to 450 watts of power, so Apple has cut the top of this graph, so it is really only showing till the top of the M1 Performance, but the other video card goes much higher.
I had seen a few videos fix the graph, and found this post from iPhone Hacks that has a fixed version of the graph from MKBHD.
This adds the power curve of the NVIDIA 3900 and the Ti should go further than this.
So yes the Mac Studio may use less power, but it gets whipped by the top of the line NVIDIA card.
It may be the most powerful Mac Graphics card, but not the most powerful graphics card that is for sure.