For clarity purposes, I set up a simulation of a flat surface up against a curved one. The setup looked like this, as viewed from the top down:

On the left is a round surface and on the right, a flat one. Both sides have three "buildings". The distances to the buildings are
identical, and the cameras are also
identical. Importantly, I added a distinctive white band to the bottom of the buildings, and a black one to the top so you can see where they are. Happy to upload the scene if anybody would like to play with it.
The output looks like this:

Notice how the furthest back building is noticeably
shorter on the left than the one on the right. The white band is also completely missing; the bottom of the building is being hidden by the curvature. On the right however, you can see the whole thing.


Zooming both cameras (keeping them still
identical) simply amplifies the effect. From this, a prediction can be made that zooming in reality maintains the missing bottom of the buildings too.