Why do some places on Earth have higher gravity than others? Sometimes the reason is unknown. To help better understand the Earth's surface, sensitive measurements by the orbiting satellites GRACE and CHAMP were used to create a map of Earth's gravitational field. Since a center for studying these data is in Potsdam, Germany, and since
Based on Wikipedia I think the unit is milligals, where a gal is 1 centimeter per second squared.
That is a bit of an odd unit where g is ~980,000 milligals.
So these changes are extremely small.
So then the total variation is all within about 0.02% of gravities normal value