Prevent seams on a generated mesh with split edges.

I've got a script that generates a procedural mesh and then splits the edges to make it flat shaded, but there's a problem when viewing it.

There are these seams that are visible at the edges, and when viewed from a distance, cluster together to make a white/yellow hue on the entire mesh.

Here are some pictures:

Here is the code:

 Mesh mesh = meshFilter.mesh;
 Vector3[] vertices = mesh.vertices;
 
 for (int i = 0; i < vertices.Length; i++) {
     float xCoord = Mathf.Abs((transform.position.x + vertices[i].x) * scale)-5000;
     float yCoord = Mathf.Abs((transform.position.z + vertices[i].z) * scale)-5000;
     vertices[i].y = (Mathf.PerlinNoise (xCoord, yCoord) - 0.5f) * power;
 }
 meshFilter.mesh.vertices = vertices;
 meshFilter.mesh.RecalculateBounds ();
 meshFilter.mesh.RecalculateNormals ();
 

 // split edges
 Vector3[] oldVerts = vertices;
 int[] triangles = mesh.triangles;
 vertices = new Vector3[triangles.Length];
 for (int i = 0; i < triangles.Length; i++) {
     vertices[i] = oldVerts[triangles[i]];
     triangles[i] = i;
 }
 mesh.vertices = vertices;
 mesh.triangles = triangles;
 mesh.RecalculateBounds();
 mesh.RecalculateNormals();
 
 meshFilter.mesh = mesh;
 meshCollider.sharedMesh = mesh;