unity – Mesh contents get flipped

I am using below shader with my mesh object that is showing a webpage. It is showing fine but the problem is the web page has flipped:

 Shader "UI/Default_OverlayNoZTest"
 {
     Properties
     {
         (PerRendererData) _MainTex ("Sprite Texture", 2D) = "white" {}
         _Color ("Tint", Color) = (1,1,1,1)
         
         _StencilComp ("Stencil Comparison", Float) = 8
         _Stencil ("Stencil ID", Float) = 0
         _StencilOp ("Stencil Operation", Float) = 0
         _StencilWriteMask ("Stencil Write Mask", Float) = 255
         _StencilReadMask ("Stencil Read Mask", Float) = 255
 
         _ColorMask ("Color Mask", Float) = 15
     }
 
     SubShader
     {
         Tags
         { 
             "Queue"="Overlay" 
             "IgnoreProjector"="True" 
             "RenderType"="Transparent" 
             "PreviewType"="Plane"
             "CanUseSpriteAtlas"="True"
         }
         
         Stencil
         {
             Ref (_Stencil)
             Comp (_StencilComp)
             Pass (_StencilOp) 
             ReadMask (_StencilReadMask)
             WriteMask (_StencilWriteMask)
         }
 
         Cull Off
         Lighting Off
         ZWrite Off
         ZTest Off
         Blend SrcAlpha OneMinusSrcAlpha
         ColorMask (_ColorMask)
 
         Pass
         {
         CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #include "UnityCG.cginc"
             
             struct appdata_t
             {
                 float4 vertex   : POSITION;
                 float4 color    : COLOR;
                 float2 texcoord : TEXCOORD0;
             };
 
             struct v2f
             {
                 float4 vertex   : SV_POSITION;
                 fixed4 color    : COLOR;
                 half2 texcoord  : TEXCOORD0;
             };
             
             fixed4 _Color;
 
             v2f vert(appdata_t IN)
             {
                 v2f OUT;
                 OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
                 OUT.texcoord = IN.texcoord;
 #ifdef UNITY_HALF_TEXEL_OFFSET
                 OUT.vertex.xy += (_ScreenParams.zw-1.0)*float2(-1,1);
 #endif
                 OUT.color = IN.color * _Color;
                 return OUT;
             }
 
             sampler2D _MainTex;
 
             fixed4 frag(v2f IN) : SV_Target
             {
                 half4 color = tex2D(_MainTex, IN.texcoord) * IN.color;
                 clip (color.a - 0.01);
                 return color;
             }
         ENDCG
         }
     }
 }

I am using above shader so that the mesh should be shown on top of everyting.