Yeah i read that and I immediately thought BS. The most the tide varies on earth is less 15 meters.
"The geoid can be as low as 106 meters (350 feet) below the ellipsoid or as high as 85 meters (280 feet) above."[1]
[1] https://www2.csr.utexas.edu/grace/gravity/gravity_definition...
In this case it’s 106m away from a perfect circle. Almost nothing compared to 20km, but a real thing.