PSA 8.5 is one of the worst grades out there for lack of any repeatability. All half grades are a joke honestly and the lower you go the worse they get, but the more infrequent they get. So 8.5’s being the most common are the biggest problem IMO.
www.elitefourum.com/t/psa-8-5-grading-anomaly-december-2016-january-2017/18738/1
www.elitefourum.com/t/bgs-10-black-label-shiny-zard/24161/131