Page 10 of the LT1243 datasheet says that the gate drive pin needs a Schottky protection diode to be connected to it (cathode to gate pin, anode to ground). https://cds.linear.com/docs/en/datasheet/1241fa.pdf
The LM3421 datasheet doesn't actually say that it is MOSFET based though?
As far as we know, the LM3421 could be mosfet based, bjt based, or BiCMOS based?
Also, isn't BJT based IC's more resilient to static electricity damage?
We are talking about high current output drivers.
I think the problem is ring in the IC to Gate trace. Some people have 4 inches of trace and it will ring and exceed one diode of kick back voltage. Because the current (edge current) is 2A, or so, the ring back has some power in it.