Is a reduced neutral conductor acceptable on a cord for use with a generator?

I purchased a 12,500 watt portable generator, a 50 amp inlet box and the corresponding 50 amp plug to power a friend's residence. I also purchased a 10’ long 50 amp range cord to connect the generator to the house via the inlet box. The cord was labeled for 50 amp service with #6/4 wiring. When I received the cord it came as a 50 amp service with #6/2 & #8/2 wiring.

My question is:
Is it acceptable to use this cord, with the reduced size neutral wire, to connect the generator to the inlet box? Any help would be appreciated. Thank you