It turns out that having a 90D does not automatically mean problems. It was in the mid 70s in the sun, and I had good rates throughout this charge. This was ten minutes in, but the taper matched what I would expect: 110kW at 32%, 86kW at 62%, stopped at 68kW and 70%.
I said it before in this thread, a 90 battery pack that is peak limited is still charging significantly faster than my old 85. If anyone is unhappy with their 90 pack and wants to swap with me, hit me up!