KLM is citing fuel price, not shortage. They’re cutting under utilized flights which they cannot perform profitably at current prices. They’ve explicitly said it’s not because of a shortage.
A shortage can also be physical. The fuel you already bought (and possibly paid for) cannot be delivered. Maybe the actual delivery is the issue. Maybe a government confiscated it for other uses. Or maybe the fuel doesn't exist at all, because the refinery didn't have the oil to produce it.