This looks like it was actually done with a dithered mode. You can see discrete dots where shading is approximated.
I don’t think this is doing what you think it’s doing.
This basically says, use a single power for the entirety of the image irrespective of grayscale level. So no matter what the picture you would just get the same burn throughout. I think this is demonstrated in what you’re seeing.
This does sound like something for grayscale as you should be able to get variable depth. Note that you won’t necessarily get variable shading on most CO2 setups.
Read through this topic on how grayscale functions. Note that this was under the context of diode lasers where variable shading can genuinely be achieved but the principle for how power is determined is the same.