UNITY_MATRIX_MVP unequal to Camera.projectionMatrix*Camera.worldToCameraMatrix*unity_ObjectToWorld?

Unity Engine
1

Hey, I try to obtain camera MVP matrix via C#Script and set to global Matrix. But the results of calculation are different from the built-in UNITY_MATRIX_MVP.
Why ?

    using UnityEngine;
    using System.Collections;
 
    public class LightProjector : MonoBehaviour {
        private Camera _lightCam;
        private Shader _replaceSdr;
        void Awake () {
            _lightCam = GetComponent<Camera>();
            _replaceSdr = Shader.Find("Hidden/LightPorject/Replace");
            if (_replaceSdr != null)
            {
                _lightCam.SetReplacementShader(_replaceSdr, "RenderType");
            }
        }
     
        void Update () { 
            Shader.SetGlobalMatrix("_LightProjectMatrix", _lightCam.projectionMatrix * _lightCam.worldToCameraMatrix);
        }
    }

ReplaceShader with UNITY_MATRIX_MVP :

    Shader "Hidden/LightPorject/Replace"
    {
        SubShader
        {
            Tags { "RenderType" = "Opaque" }
            LOD 100

            Pass
            {
                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                // make fog work
                #pragma multi_compile_fog

                #include "UnityCG.cginc"

                struct appdata
                {
                    float4 vertex : POSITION;
                    float3 normal : NORMAL;
                };

                struct v2f
                {
                    float4 vertex : SV_POSITION;
                    float3 normal : TEXCOORD0;
                };

                float4x4 _LightProjectMatrix;

                v2f vert (appdata v)
                {
                    v2f o;
                    o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                    o.normal = mul(unity_ObjectToWorld, float4(v.normal,0)).xyz;
                    return o;
                }
            
                fixed4 frag (v2f i) : SV_Target
                {
                    fixed4 col = fixed4(i.normal,1);
                    return col;
                }
                ENDCG
            }
        }
    }

ReplaceShader with (Camera.projectionMatrix * Camera.worldToCameraMatrix) * unity_ObjectToWorld :

    Shader "Hidden/LightPorject/Replace"
    {
        SubShader
        {
            Tags { "RenderType" = "Opaque" }
            LOD 100
 
            Pass
            {
                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag
                // make fog work
                #pragma multi_compile_fog
 
                #include "UnityCG.cginc"
 
                struct appdata
                {
                    float4 vertex : POSITION;
                    float3 normal : NORMAL;
                };
 
                struct v2f
                {
                    float4 vertex : SV_POSITION;
                    float3 normal : TEXCOORD0;
                };
 
                float4x4 _LightProjectMatrix;
 
                v2f vert (appdata v)
                {
                    v2f o;
                    float4 wPos = mul(unity_ObjectToWorld, v.vertex);
                    o.vertex = mul(_LightProjectMatrix, wPos);
                    o.normal = mul(unity_ObjectToWorld, float4(v.normal,0)).xyz;
                    return o;
                }
             
                fixed4 frag (v2f i) : SV_Target
                {
                    fixed4 col = fixed4(i.normal,1);
                    return col;
                }
                ENDCG
            }
        }
    }

2

I got it.

    using UnityEngine;
    using System.Collections;
    public class LightProjector : MonoBehaviour {
        private Camera _lightCam;
        private Shader _replaceSdr;
        void Awake () {
            _lightCam = GetComponent<Camera>();
            _replaceSdr = Shader.Find("Hidden/LightPorject/Replace");
            if (_replaceSdr != null)
            {
                _lightCam.SetReplacementShader(_replaceSdr, "RenderType");
            }
        }
    
        void Update () {
        Matrix4x4 zOffset = Matrix4x4.identity;
        zOffset.m22 = 0.5f;
        zOffset.m23 = 0.5f;
            Shader.SetGlobalMatrix("_LightProjectMatrix", zOffset * _lightCam.projectionMatrix * _lightCam.worldToCameraMatrix);
        }
    }