Why is shader behavior different between Android and iOS?

I am developing a game for iOS and Android. I had to write my own shaders which are basically just transparent diffuse shader with a specific queue value so that I can control what gets drawn over/under other things. The shaders work perfectly on iOS, but I get some strange behavior on Android. The issue is particularly with my fake shadows, which consist of a plane with a shadow texture. On Android the shadows appear to be higher up on the object than on iOS. I've attached some screenshots to compare.

Any idea what would cause this?

Here is my shader code:

 Shader "Custom/shadow" {
     Properties {
         _Color ("Main Color", Color) = (1,1,1,1)
         _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
     }
     SubShader {
         Blend SrcAlpha OneMinusSrcAlpha
         Cull Off
         Zwrite Off
         Tags {"Queue" = "Transparent+9" "IgnoreProjector"="True" "RenderType"="Transparent"}
         LOD 200
         
         BindChannels
         {
             Bind "vertex", vertex
             Bind "color", color
             Bind "texcoord1", texcoord
         }
         
         Pass
         {
             SetTexture[_MainTex] // Combine texture alpha
         }
         
         CGPROGRAM
         #pragma surface surf Lambert alpha
 
         sampler2D _MainTex;
         fixed4 _Color;
 
         struct Input {
             float2 uv_MainTex;
         };
 
         void surf (Input IN, inout SurfaceOutput o) {
             fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
             o.Albedo = c.rgb;
             o.Alpha = c.a;
         }
         ENDCG
     } 
 }

iOS:

Android:

Another strange thing on Android, when I draw a line the shadows change even more:

Also note that transparent cutout shaders seem to work fine, but I get an error in the android build about incompatibility with qualcomm chips.