Question artifacts on the surface of the terrane

for the test, I created a terrain and set the height of a certain surface, I noticed that on the surface there are shadows that should not be there, in the screenshots I show how it looks.

standard urp project, standard terrain, standard light...

 

hmmm. it all looks fine and as expected!?
could you mark what you think is a false shadow?

 

look at the surface of the top and the right side, the surface itself is absolutely flat and then there is a sharp drop in height, so the surface should be white, and there is something like a shadow on it, and I want to note that if the shadow is completely removed, then these artifacts are still there. ..

 

the sharp drop does nor result in a fully upright edge. in fact the profile looks like in my overpaint: even the sharpest drop will result in a slope when it comes to a heightmap based terrain.
so the darkening you see is caused by a) n dot l lighting (correct) and shadows (also correct).

 

A terrain is rendered as a grid of small quads (two triangles each). The texture mapped on them will always look sharp and jagged if you have significant jumps in the Y value for those intersecting quads. However, the lighting system for terrain will try to "smooth" the change in normals, so you don't get color banding on subtle or minimal changes in slope. This ends up making the last vertex before a large plunge have a strongly deflected normal, causing highlights and darkening at those edges.