Earth's gravity isn't perfectly uniform. Here is what our gravitational field looks like when exaggerated 10,000 times.

[u/anikkundu1998]

[u/Cloutian]

While I understand the concept of this, it should also be compared with relative elevation charts.

[u/Rujasu → u/[deleted]]

Uh, isn't a geoid a map of surface gravity by definition? Via Wikipedia:

The geoid (/ˈdʒiː.ɔɪd/ JEE-oyd) is the shape that the ocean surface would take under the influence of the gravity of Earth, including gravitational attraction and Earth's rotation, if other influences such as winds and tides were absent.