The gravity of Earth varies on the different location on Earth. The variation is caused by the difference in latitude, altitude or depth, and local geology & topography. In most cases, the centrifugal acceleration from Earth’s rotation is also already accounted for in the value of Earth’s gravitational acceleration.
Flat-Earthers claim that according to science, the Earth’s gravitational acceleration is always constant at 9.8 m/s² everywhere on Earth. And they are using the claim to prove Earth is not a rotating sphere. In reality, the magnitude of Earth’s gravitational acceleration varies on the different location on Earth.