It’s possible that everyone locally simultaneously is wrong. ;)
Also possible your lap record holder set his best lap on lap two and then fell off too.
I agree that your pressures are too high. As Rene said, if the kart comes in on lap 2 and then falls off rapidly, your pressures are simply too high. The tire is designed for half the air you’re running. Keep in mind that air affects the way the tire physically works too, and changes the contact patch.