I unfortunately dismantled it already, but I played my last nightfall: the ordeal for the week to round out my powerful gear challenge for the week and I got no piece of gear that was above any of the currently owned gear of that slot. However, I did get a piece of shadowkeep chest gear that dropped at 750. I thought this was strange since my powerful drops are now all at 950. It was also especially strange to see a piece of gear new to shadowkeep to drop at 750. My guess is that this is a bug that's happening because some constant that denotes the max power level for that season was not updated somewhere in the code.