Can't Get Simple Transparency Shader To Work

Hi everyone, I'm trying to build a shader for transparent sprites, which can adjust the alpha of the sprites using a Range() variable. However, when I try adjusting the alpha of the sprite in my fragment shader it causes a solid background to appear behind the transparent sprite. I included the code for reference.

 Shader "TransparentShader"
 {
     Properties
     {
         _MainTex("Texture1", 2D) = "white" {}
         _Tween("Tween", Range(0,1)) = 0.0
     }
 
     SubShader
     {
         Tags
         {
             "Queue" = "Transparent"
             "RenderType"="Transparent"
         }
 
         Pass
         {
             Blend SrcAlpha OneMinusSrcAlpha
 
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #include "UnityCG.cginc"
 
             struct appdata 
             {
                 float4 vertex : POSITION;
                 float2 uv : TEXCOORD0;
             };
 
             struct v2f
             {
                 float4 vertex : SV_POSITION;
                 float2 uv : TEXCOORD0;
             };
 
             v2f vert(appdata v) {
                 v2f o;
                 o.vertex = UnityObjectToClipPos(v.vertex);
                 o.uv = v.uv;
                 return o;
             }
 
             sampler2D _MainTex;
             float _Tween;
 
             float4 frag(v2f i) : SV_TARGET
             {
                 float4 color = tex2D(_MainTex, i.uv);
 
                 // WORKS WITH TRANSPARENCY
                 //return color;
 
                 // RENDERS A SOLID SPRITE BACKGROUND??
                 return float4(color.r, color.g, color.b, 0.5);
             }
 
             ENDCG
 
         }
     }
 
 }
 

When returning a float4 with modified alpha. When returning the original texture's color.