I got that as well on my test parts. I put up a picture in the new center thread. Mine weren’t off by that far .2mm on inside and outside cuts. Equal on both the x and y axis. I could adjust the bit diameter but that I wouldn’t get equal dimension on inside and outside cuts. I am not sure if it is a machine or a software thing. With the correct bit diameter I got equal inner and out .2mm small, that leads me to believe it might be a resonance (machine thing) like the vibration adding .2mm, .1mm on either side of the bit. This is on the new center, with 55% infill, I am almost done printing a set with 70% infill. I want to see if infill has a direct effect.
Sorry that was kinda off topic.
For you, if it is what I am thinking. Try the same cut with the same settings but make sure you have the z axis at a minimum length (raise your material to as close as you can possibly get it to the gantry. If your tolerances get tighter I was right. How to solve that….not sure the best route yet. Maybe its rigidity, maybe belt tension, maybe a sloppy tool, so many variables.
If you had it all the way up already, lower it and try again, if they get worse I am still on the right track.