This doesn't bode well.
Selective schools getting Exceptionals for achievement is the precise opposite of what the system is supposed to be about.
Back in the day, when we had 5A*-C, the top spots were dominated by leafy suburban schools (often faith schools) with stealth-selected intakes and very low levels of free school meals.
Progress 8 came along, and started the good work of levelling the field. I'm not convinced it does enough, but it's a great start.
If Ofsted continue to disproportionately give selective schools Exceptional for achievement, then they will lose whatever small support they have left, as well as undoing the direction of travel set by Progress 8.
And achievement grades by same admissions classifications