A weighing scale measures mass by measuring the gravitational force exerted by the object we measure. Because the magnitude of the force depends on the strength of the gravitational acceleration, the result can vary depending on the location. It is the reason the scale needs to be calibrated after it is moved to another location.
On the other hand, a balance measures mass by comparing the object’s mass to a previously known mass. Because both masses are affected by the same gravitational acceleration, a balance is not affected by the change in gravitational acceleration.
Moving a scale to another location can change the measurement results due to the variation in Earth’s gravitational acceleration. Flat-Earthers tried to repeat the result using a balance & failed to replicate it. Then they use their failure to discredit science. In reality, because a balance works by comparing an unknown with a known mass, it is unaffected by the change in gravitational acceleration.