High 2 & 3 hour power/Fat vs Carb usage

My 2 and 3 hour power numbers are 317 and 307W respectively. Also my fat vs carb usage seems heavily skewed towards fat, I don’t seem to register much carb until power approaches 300W.

The power numbers look high to me. Not sure what they are based on as I have never had a ride that high. My best 2 hour normalised power is around 290W and 3 hour 275W.

I’m guessing these numbers also are the reason my fat usage is higher than I would expect?

Can you explain the calculation behind these numbers please.