I have no real issue with the AF on my R6 which is the same system although i have come across a couple of situations that do confuse it(most notably zebras). And that is with ef lenses and adapter(both canon and third party lenses). As for IQ. I find my 20mp R6 images to be sharper across the board than my 7d2 images and with close to 3 stops of improved noise performance(i have auto ISO limited to 6400 but if need be will push to 12800 in certain circumstances as long as I dont have to crop). So I would say it is either a defective body or as has been said before, possibly a body/lens comunnication issue.