Shader problem with multiple prefab instances

Questions & Answers
1

I made a prefab with simple cube and applied “Display Normals” shader to check the normal of faces of the model.

If I put one prefab instance into the scene, rotation of the model does not change face colors. But if I put one more instance into the scene the face colors of both two instances change immediately. Face colors varies when I rotate them.

It seems like the face color is decided not by local coordinate but world coordinate with multiple prefab instances. Is this a bug or just a improper setting problem?

84742-a.png

84743-b.png

Shader "Display Normals" {
	SubShader{ 
		Pass{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"

			// vertex input: position, normal
			struct appdata 
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL; 
			};

			struct v2f 
			{
				float4 pos : SV_POSITION;
				fixed4 color : COLOR;
			};

			v2f vert(appdata v)
			{
				v2f o;
				o.pos = UnityObjectToClipPos(v.vertex);
				o.color.xyz = v.normal * 0.5 + 0.5;
				o.color.w = 1.0;
				return o;
			}

			fixed4 frag(v2f i) : SV_Target{ return i.color; }
				ENDCG
		}
	}
}
2

I’ve upgraded from 5.4.1f1 to 5.5.0f3 and it seems like working well.
And there was a thread about similar problem.
https://forum.unity3d.com/threads/dynamic-batching-seems-to-modify-preset-vertex-normals-and-tangent-is-this-fixable.240882/#post-1595874