Smooth lightning problem Procedural Generation

Hello!
I'm trying to make a Procedural Generation system, but I have a problem.

The terrain lightning doesn't look like smooth.
Here is the code :

Code (CSharp):

1. using System.Collections.Generic;
2. using UnityEngine;
3.  
4. public class Map : MonoBehaviour
5. {
6.     public MeshFilter m_MeshFilter;
7.     public MeshRenderer m_MeshRenderer;
8.     public Material Mat;
9.     public float XSize = 5f;
10.     public float ZSize = 5f;
11.     public float YCoef = 2f;
12.  
13.     // Start is called before the first frame update
14.     void Start()
15.     {
16.         Mesh NewMesh = new Mesh();
17.         Vector3[] Vertices = new Vector3[(int)XSize * (int)ZSize * 4];
18.         List<int> Triangles = new List<int>();
19.  
20.         int CurrentVertice = 0;
21.         int LastZ = 0;
22.  
23.         for (int Z = 0; Z < ZSize; Z++)
24.         {
25.             Vertices[CurrentVertice] = new Vector3(0, Mathf.PerlinNoise(0, LastZ / ZSize * 10) * YCoef, Z);
26.             Vertices[CurrentVertice + 1] = new Vector3(0, Mathf.PerlinNoise(0, Z  / ZSize * 10) * YCoef, Z + 1);
27.             CurrentVertice += 2;
28.             for (int X = 0; X < XSize; X++)
29.             {
30.                 Vertices[CurrentVertice] = new Vector3(X + 1, Mathf.PerlinNoise((X + 1) / XSize, LastZ / ZSize * 10) * YCoef, Z);
31.                 Vertices[CurrentVertice + 1] = new Vector3(X + 1, Mathf.PerlinNoise((X + 1) / XSize, Z / ZSize * 10) * YCoef, Z + 1);
32.  
33.  
34.                 Triangles.Add(CurrentVertice - 2);
35.                 Triangles.Add(CurrentVertice - 1);
36.                 Triangles.Add(CurrentVertice);
37.  
38.                 Triangles.Add(CurrentVertice - 1);
39.                 Triangles.Add(CurrentVertice + 1);
40.                 Triangles.Add(CurrentVertice);
41.  
42.                 CurrentVertice += 2;
43.             }
44.             LastZ = Z;
45.         }
46.  
47.         //Generate UVS
48.         Vector2[] uvs = new Vector2[Vertices.Length];
49.         for (int i = 0; i < uvs.Length; i++)
50.             uvs[i] = new Vector2(Vertices[i].x, Vertices[i].z);
51.  
52.         //Set mesh
53.         NewMesh.vertices = Vertices;
54.         NewMesh.uv = uvs;
55.         NewMesh.triangles = Triangles.ToArray();
56.         NewMesh.RecalculateNormals();
57.         m_MeshRenderer.material = Mat;
58.         m_MeshFilter.mesh = NewMesh;
59.     }
60. }

Can you help me?
Thanks!

Sorry for my english lol