LT8708 in buck mode, input 48V output 43V with load more than 0.3A burn MOSFET

Product Specifications: Input: 12.5-75V Output: 43V 7A

LT8708 step-down mode, input 48V output 43V, load > 0.3A burning MOSFET

With load M1 M2 MOSFET damage, short circuit

No-load output voltage is normal, input 12V boost output 43V is normal

However, at 48V input and 43V output, the MOSFET with the load of M1 M2 is damaged and transmitted, short circuit

What is the cause of this problem?