@barely if your inverters support it look to have them configured for production ramp down at high frequencies. For my Enphase inverters I've applied the grid profile that enables this and effectively ramps down the solar production after the frequency rises past 60.20 Hz. This prevents the "flip flop" effect you're seeing at high SOCs during the day when solar is being produced.
Start frequency 60.20 Hz
Start delay 0.0 ms
Ramp down rate 83.00 %/Hz
Thanks @gpez. It's a SolarEdge SE7600H. I'll start looking through the manual and see what I can find.