Interesting....and that is with the 1DX III image being at ISO 8000. The 5DIV image is ISO 2000, R5 image is ISO 1600, and M6 II image is ISO 640.
Not a controlled test, for sure.
I thought the top three were adequate and fairly equal. I faulted the bottom and it turned out to be the 1Dx III. It may have been the high ISO, but the eye wasn't as crisp as the other three.