LTC3892-1 in DRVcc=5 configuration has a gate drive current of around 510mA instead of 2A

I used LTC3892-1 as a 20A output 32V -> 12V DCDC converter. I have the DRVSET set to 50k, so the DRVcc is 5V. The circuit was also simulated in LTSpice and seemed to be correct.

The configuration is:

DRVUV = 49.9K (5V)

FREQ = 54.9k (350kHz)

GaNFETs = EPC2206, 19nC charge / 5V at the gate

My rise time is 37ns vs 10-20ns estimated/simulated. The measured peak gate current (diff probe at 0.1 Ohm shunt at BG) is around 510 mA. How do I increase the drive strength?