Unexpected behavior in Vertex/Fragment shader when using saturate method (CG)

Im learning shader writing lately and now im trying to write a simple snow shader which blends 2 textures based on the snowdirection. At the moment, the snowmask looks like i want it to (black and white mask in unity viewport), but when i apply a saturation method to it, it seems all pure black pixels in the shadows turn white. I dont understand why because in my understanding, the saturation method should not make dark pixels (<= 0) to white (1). What is happening?

 Shader "Simple Snow Shader2" 
 {
 
     Properties
     {
         _MainTex("Base (RGB)", 2D) = "white" {}
         _SnowDirection("Snow Direction", Vector) = (0,1,0)
         _SnowFalloff("Snow Falloff", float) = 1.0
         _SnowTiling("Snow Tiling", float) = 1.0
     }
 
     SubShader
     {
         Pass
         {
             CGPROGRAM
             #pragma vertex vert  
             #pragma fragment frag 
             #include "UnityCG.cginc"
 
             sampler2D _MainTex;
             float4 _SnowDirection;
             float _SnowFalloff;
             float _SnowTiling;
         
 
             struct vertexInput 
             {
                 float4 vertex : POSITION;
                 float4 tangent : TANGENT;
                 float4 uv : TEXCOORD0;
                 float3 normal : NORMAL;
                 fixed4 color : COLOR;
             };
     
             struct vertexOutput 
             {
                 float4 pos : SV_POSITION;
                 float4 col : TEXCOORD0;
                 float4 worldnormal : NORMAL;
                 float2 uv : TEXCOORD1;
             };
 
             vertexOutput vert(vertexInput input)
             {
                 vertexOutput output;
                 output.pos = mul(UNITY_MATRIX_MVP, input.vertex);
                 float4 worldnormal = mul(_Object2World, float4(input.normal, 0.0));
                 output.worldnormal = worldnormal;
                 output.col = input.color;
                 return output;
             }
 
             float4 frag(vertexOutput input) : COLOR
             {
         
                 float4 diffuse = tex2D(_MainTex, input.uv);
                 float4 snowmask = pow(dot(input.worldnormal, _SnowDirection), _SnowFalloff);
                 //input.col = saturate(snowmask);
                 input.col = (snowmask);
 
                 return input.col;
             }
 
             ENDCG
         }
     }
 }