So, as a general rule, the beam isn’t really going to lose energy over a distance like this. Either the energy gets eaten up/absorbed by something in the beam path, or the energy is delivered into a larger area, so it has less of an impact on the material (focus).
I would check all of the optics (two windows and the lens) and remove the top of the head (it’s magnetic) to make sure the mirror is seated properly and not damaged.
I would also take the crumbtray out and put it on a flat surface and see if you have some kind of deformity/manufacturing error.
And if I didn’t find anything there, I would put it back in, and using calipers, I would measure the distance from the bottom of the head down to the crumbtray surface and make sure it’s within a few thousandths of an inch at all corners.