Shader works in editor but not on Android

Hello!

This is the shader I am trying to use. I did not write it. I got it on the web.

 Shader "Custom/Scanlines" {
     Properties{
         _Color("Color", Color) = (0,0,0,1)
         _LinesSize("LinesSize", Range(1,10)) = 1
     }
         SubShader{
             Tags {"IgnoreProjector" = "True" "Queue" = "Overlay"}
             Fog { Mode Off }
             Pass {
                 ZTest Always
                 ZWrite Off
                 Blend SrcAlpha OneMinusSrcAlpha
 
         CGPROGRAM
 
         #pragma vertex vert 
         #pragma fragment frag
         #include "UnityCG.cginc"
 
                 fixed4 _Color; half _LinesSize;
 
                 struct v2f {
                     half4 pos:POSITION;
                     fixed4 sPos : TEXCOORD;
                 };
 
                 v2f vert(appdata_base v) {
                     v2f o; o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                     o.sPos = ComputeScreenPos(o.pos);
                     return o;
                 }
 
                 fixed4 frag(v2f i) : COLOR {
                     fixed p = i.sPos.y / i.sPos.w;
 
                     if ((int)(p*_ScreenParams.y / floor(_LinesSize)) % 2 == 0) discard;
 
                        return _Color;
                  }
 
         ENDCG
                }
 
     }
 
 }

And this is the script I am using to load it. It is attached to the camera.

 using UnityEngine;
 
 [ExecuteInEditMode]
 public class CRTShader : MonoBehaviour {
 
     private Material material;
 
     void Start() {
         material = new Material(Shader.Find("Custom/Scanlines"));
     }
 
     public void OnRenderImage(RenderTexture source, RenderTexture destination) {
         material.SetTexture("_MainTex", source);
         Graphics.Blit(source, destination, material);
     }
 
 }

It runs fine on the editor but it does not work on the Android build.

The shader is in the Resources folder.

What I am doing wrong? Any ideas?

Thank you.