Bug? Spots of maximal ambient occlusion

Is it a bug?

I get strange spots of maximal ambient occlusion.
To reproduce the problem I set up a little example.

What I’ve done:

*added a Plane
*subdivide it several times
*applied a displacement mod with a cloud texture
*setup ambient occlusion (set pink color to highlight it)
*set auto smooth to as smooth as can be (180°)

As result I got a mesh with strange spots with maximal ambient occlusion. (Pic 1)
When I triangulate the mesh it gets better but there are still a strange spots. (Pic 2)
Rendered with Eevee there seems to be no such behavior. (Pic 3)

What can I do as workaround? Adding much more geometry is not option for me because my original mesh is a very large landscape and my system is on it’s limit.

I’ve uploaded the .blend File
( alternative .blend download )

Strange. I think its due to the low mesh resolution, try something like this:

Unfortunately, this doesn’t work with my real mesh for unknown reason.

Interesting, i’m using the file you provided. what version of Blender are you using?

edit: i see what you’re saying now. Can you cut out a chunk of it with the errors and share it? i feel like mesh optimization may save you here

I think you are right. My mesh seems totally messy from trying too much.
Here is an excerpt from my mesh.
I think there are other mistakes there. If you move the “mesh island” to which the coordinate origin is located, the error disappears.

( I have to say that I am a beginner to Blender )

I managed to correct my mesh. With CorretiveSmooth and Weld modifier I got acceptable results.
I just don’t understand why this situation came about in the first place.

Thanks for the help, the mesh topology was the reason.