Raymarching - bad shadows/light quality on fractals

Hello, i am experimenting with some raymarching shaders & fractals, but i my shadow/light quality is really bad on my fractals, but on sphere/any other objects it works completly fine, any ideas?

My code here:

 Shader "Ondy/RayMarch"
 {
     Properties
     {
         _mainColor ("MainColor", Color) = (.25, .5, .5, 1)
         _MainTex ("Texture", 2D) = "white" {}
         ScaleX ("ScaleX", Float) = 1
         ScaleY ("ScaleY", Float) = 1
         ScaleZ ("ScaleZ", Float) = 1
     }
     SubShader
     {
         Tags { "RenderType"="Opaque" }
         LOD 100
         Cull off
 
         Pass
         {
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #pragma target 3.0
 
             #include "UnityCG.cginc"
             #include "DistanceFunctions.cginc"
 
             uniform fixed4 _mainColor;
             uniform float ScaleX;
             uniform float ScaleY;
             uniform float ScaleZ;
             uniform float3 _LightDir;
 
 #define MAX_STEPS 164
 #define MAX_DIST 150
 #define SURF_DIST 1e-4
 #define _LightDir (1, 1, 1)
 
             struct appdata
             {
                 float4 vertex : POSITION;
                 float2 uv : TEXCOORD0;
             };
 
             struct v2f
             {
                 float2 uv : TEXCOORD0;
                 float4 vertex : SV_POSITION;
                 float3 ro : TEXCOORD1;
                 float3 hitPos : TEXCOORD2;
             };
 
             sampler2D _MainTex;
             float4 _MainTex_ST;
 
             v2f vert (appdata v)
             {
                 v2f o;
                 o.vertex = UnityObjectToClipPos(v.vertex);
                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                 o.ro = _WorldSpaceCameraPos;
                 o.hitPos = mul(unity_ObjectToWorld, v.vertex);
                 return o;
             }
 
             float GetDist(float3 p)  
             {
                 float d = sdBox(p - 2,float3(1, 1, 1));
                 //float3 res = float4( d, 1.0, 0.0, 0.0 );
                 float xd = sdSphere(p, float3(1, 1, 1));
 
                 float s = 1.0;
                 for( int m=0; m<4; m++ )
                 {
                     float3 a = fmod( p * s, 2.0 ) - 1;
                     s *= 3.0;
                     float3 r = abs(1.0 - 3 * abs(a));
 
                     float da = max(r.x,r.y);
                     float db = max(r.y,r.z);
                     float dc = max(r.z,r.x);
                     float c = (min(da,min(db,dc))-1)/s;
 
                     d = max(d,c);
 
                     //if( c > d )
                     //{
                     //    d = c;
                     //    res = float4( d, 0.2*da*db*dc, (1.0+float(m))/4.0, 0.0 );
                     //}
                 }
                 //return res;
                 return float3(d, 1, 1);
             }
 
             float Raymarch(float3 ro, float3 rd) 
             {
                 float dO = 0;
                 float dS;
 
                 for(int i = 0; i < MAX_STEPS; i++)    
                 {
                     float3 p = ro + dO * rd;
                     dS = GetDist(p);
                     dO += dS;
                     if (dS<SURF_DIST || dO>MAX_DIST) break;  
                 }
 
                 return dO;
             }
 
             float3 GetNormal(float3 p)
             {
                 const float2 e = float2(1e-2, 0);
                 float3 n = float3( 
                     GetDist(p + e.xyy) - GetDist(p - e.xyy),
                     GetDist(p + e.yxy) - GetDist(p - e.yxy),
                     GetDist(p + e.yyx) - GetDist(p - e.yyx)
                 );
                 return normalize(n);
             }
 
             fixed4 frag (v2f i) : SV_Target
             {
                 float2 uv = i.uv-.5;
                 float3 ro = i.ro; //float3(0, 0, -3);
                 float3 rd = normalize(i.hitPos-ro); //normalize(float3(uv.x, uv.y, 1));
 
                 float d = Raymarch(ro, rd);
                 fixed4 col = 0;
 
                 if(d >= MAX_DIST){
                     //discard;
                 }
                 else{
                     float3 p = ro + rd * d;
                     float3 n = GetNormal(p);
                     float light = dot(-_LightDir, n);
                     //col.rgb = n *+- light;
                     col.rgb = light * _mainColor;   
                 }
 
                 //if(d < MAX_DIST){
                 //    float3 p = ro + rd * d;
                 //    float3 n = GetNormal(p);
                 //    col.rgb = n;
                 //    //col.rgb = _mainColor;
                 //}
 
                 return col;
             }
             ENDCG
         }
     }
 }