The Color output of the Scene Texture node has 4 components (RGBA) your Custom Node is setup to return float3 (RGB). Change the return type of your Custom Node to float4 and everything should be fixed.
The Color output of the Scene Texture node has 4 components (RGBA) your Custom Node is setup to return float3 (RGB). Change the return type of your Custom Node to float4 and everything should be fixed.