That explanation raises more questions than answers. The deepest known point, The Mariana Trench is alleged to be 11 km deep. That model appears to indicate that it is a canyon on elevation. It then places a very massive indentation (by the deep blue indicator) on the opposite side of the continent of Asia.
In this video and by scientific calculations, the amount of water on Earth does not equal a very large mass. Leaving the Earth to still appear quite uniform and spherical in shape. (1:49)
I don't treat YT videos are science but Riddle at least tries to keep it factual. It's just hard to accept that the Earth would look like that without water. One then must believe that some areas of the ocean are close to or more than 100 kilometers deep.
only if one assumes that when the water is added, the result is a perfect circle (because yes, that would be the approximate level of water needed to return the height of the deeper valleys up to the level that kind of level).
However, we know the world is far from a perfect sphere, as is demonstrated both from our InSAR radar satellites and also ground-based observations showing differences in how far you can see on the ground.
So long story made short: When you add water to the image in the video I linked, it becomes less extreme, but still far from a perfect sphere.
In Riddler's video, there isn't near enough water to fill even a small area of those valleys. Thus in that Earth, the above sea level measurements would give some extreme readings in many regions of Earth.
Coincidentally, from the perspective of human, we would also see some bizarre anomalies in many regions. A rising horizon such as when one is at the foot of a mountain range would be a common sight. One would observe gigantic mountain ranges. From the perspective of Brazil facing towards Chile for instance.
I don't mean to discredit you nor the scientific community here. I'm merely questioning what logic determines as a clear discrepancy. Which evidently, is why the conspiracy of Flat Earth has grown in magnitude in recent years.
There ARE conflicting 'truths' within the science community and from reputable organizations, which in turn fuel speculation. Proclaimed images of Earth by NASA vs the now standardized version of a lumpy Earth alone would mean that one is a fallacy.