Question Shader looks fine in Editor, not so nice in Standalone

I have this shadow sprite:
On my map, which is shown above. Pictures are from the editor.
When I try to build it to the same machine I am developing on, this is what it looks like:




It essentially looks like a grey/white overlay on top of the sprites, which differs a lot from how it's presented in the Unity Editor. I am very unsure how to debug this. The sprite itself looks fine if I change the layer and render it outside of the shader. Another potential important information is I am rendering this through a render texture.
I didn't really touch the default settings much, but I adjusted the aspect ratio to fit the game (1280:720) Wrap mode is clamp, filter-mode is point

Code (CSharp):

1. Shader "Custom/Shadows-Mask-Default"
2. {
3.     Properties
4.     {
5.         _MainTex ("Texture (RGB)", 2D) = "white" {}
6.         _MaskTex ("Mask (A)", 2D) = "white" {}
7.     }
8.  
9.     SubShader
10.     {
11.         Tags { "Queue"="Transparent" "RenderType"="Transparent" }
12.         LOD 100
13.         Blend SrcAlpha OneMinusSrcAlpha
14.  
15.         Pass
16.         {
17.             CGPROGRAM
18.             #pragma vertex vert
19.             #pragma fragment frag
20.  
21.             #include "UnityCG.cginc"
22.  
23.             struct appdata
24.             {
25.                 float4 vertex : POSITION;
26.                 float2 uv : TEXCOORD0;
27.             };
28.  
29.             struct v2f
30.             {
31.                 float2 uv : TEXCOORD0;
32.                 float4 vertex : SV_POSITION;
33.             };
34.  
35.             sampler2D _MainTex;
36.             sampler2D _MaskTex;
37.  
38.             v2f vert (appdata v)
39.             {
40.                 v2f o;
41.                 o.vertex = UnityObjectToClipPos(v.vertex);
42.                 o.uv = v.uv;
43.                 return o;
44.             }
45.  
46.             fixed4 frag (v2f i) : SV_Target
47.             {
48.                 fixed4 color = tex2D(_MainTex, i.uv);
49.                 fixed4 mask = tex2D(_MaskTex, i.uv);
50.  
51.                 color.a *= mask.a;
52.                 return color;
53.             }
54.             ENDCG
55.         }
56.     }
57. }
58.  

The purpose of this shader is to ensure none of the shadow sprite is rendered on the outside of the default layer (green terrain), so that the purple layer (background) stays clear. The sort order has the shadows on top, hence I had to be creative in order to ensure the shadow didn't render on top of the green map.

I tried:
- Changing color mode from Gamma to Linear
- Change fixed4 to float4
- Disabling shader stripping

Alas no luck in fixing this.

 

Do you use mutliple quality tiers?

 

I haven't really touched the quality settings, but now I tried to force it on ultra with no other allowed settings, although still no change. :/

I also tried to change the blend to see if it had an impact to
Blend One OneMinusSrcAlpha




It seemingly made it worse
Oh also, I am using URP 2D renderer