Fog is now computed outside the simple lighting function.

com.unity.render-pipelines.lightweight/LWRP/ShaderLibrary/Lighting.hlsl

     finalColor += specularColor;
 #endif
 
-    ApplyFog(finalColor, inputData.fogCoord);
     return half4(finalColor, alpha);
 }
 #endif

com.unity.render-pipelines.lightweight/LWRP/ShaderLibrary/LightweightPassLitSimple.hlsl

     InputData inputData;
     InitializeInputData(IN, normalTS, inputData);
 
-    return LightweightFragmentBlinnPhong(inputData, diffuse, specularGloss, shininess, emission, alpha);
+    half4 color = LightweightFragmentBlinnPhong(inputData, diffuse, specularGloss, shininess, emission, alpha);
+    ApplyFog(color.rgb, inputData.fogCoord);
+    return color;
 };
 
 #endif

com.unity.render-pipelines.lightweight/LWRP/ShaderLibrary/Terrain/LightweightPassLitGrass.hlsl

     InputData inputData;
     InitializeInputData(IN, inputData);
 
-    return LightweightFragmentBlinnPhong(inputData, diffuse, specularGloss, shininess, emission, alpha);
+    half4 color = LightweightFragmentBlinnPhong(inputData, diffuse, specularGloss, shininess, emission, alpha);
+    ApplyFog(color.rgb, inputData.fogCoord);
+    return color;
 };
 
 #endif