DRV8340-Q1: Zener Clamp Diode

Dear expert,

The customer has some question about DRV8340 integrated zener clamp diode.

1. Why external short-circuit events on the MOSFET will cause a overvoltage  HS VGS?
2. Why doesn't low side have a zener clamp diode?
3. If the external MOSFET VGS tolerance is +/-16V, Does the high side need an external zener clamp diode? As the integrated positive clamping voltage range is from 15V to 19V.

Thank you,

Dylan