Vertex Shader bug in Mobile with noise screen effects

Hello Everyone,

I started to migrate my models to accept vertex colors, but as soon as I tested in mobile, some weird shaking noise effect started:

I don't know what is happening, any help will be very appreciated. This is my vertex shader, It is very simple. I multiply with an image that I use as AO. I already tried with only vertex colors but nothing works.

 SubShader
     {
         Tags { "RenderType"="Opaque" }
         LOD 200
         
         CGPROGRAM
         // Physically based Standard lighting model, and enable shadows on all light types
         #pragma surface surf Standard fullforwardshadows vertex:vert
 
         // Use shader model 3.0 target, to get nicer looking lighting
         #pragma target 3.0
 
         sampler2D _Main2Tex;
 
         struct Input
         {
             float3 vertColor;
             float2 uv_Main2Tex : TEXCOORD0;
         };
 
         void vert (inout appdata_full v, out Input o)
         {
             UNITY_INITIALIZE_OUTPUT(Input, o);
             o.vertColor = v.color;
         }
 
         void surf (Input IN, inout SurfaceOutputStandard o)
         {
             fixed4 ao = tex2D (_Main2Tex, IN.uv_Main2Tex);
             o.Albedo = IN.vertColor.rgb * ao.rgb;
         }
         ENDCG
     }
     FallBack "Diffuse"