Make sure the sky fully overwrites unoccluded parts of the frame

Assets/ScriptableRenderLoop/HDRenderLoop/Sky/ProceduralSky/Resources/SkyProcedural.shader

                 float3 atmosphereColor = skyColor * (skyTexWeight * extinction) + scatter;
 
                 // Apply the atmosphere on top of the scene using premultiplied alpha blending.
-                return float4(ClampToFloat16Max(atmosphereColor), extinction);
+                float opacity = (skyTexWeight == 1.0) ? 1.0 : extinction;
+
+                return float4(ClampToFloat16Max(atmosphereColor), opacity);
             }
 
             ENDHLSL