Including TIR in iridescence F reflectance, useful when using dual normal maps (only for stacklit).

com.unity.render-pipelines.core/CoreRP/ShaderLibrary/BSDF.hlsl

     // real eta_2 = lerp(eta_1, eta_2, smoothstep(0.0, 0.03, Dinc));
     // Evaluate the cosTheta on the base layer (Snell law)
     real sinTheta2 = Sq(eta_1 / eta_2) * (1.0 - Sq(cosTheta1));
-    //debug: TIR if( sinTheta2 > 1.0 ) return real3(1.0, 0.0, 0.0);
+#ifdef UNITY_MATERIAL_STACKLIT
+    //TIR 
+    if( sinTheta2 > 1.0 ) return real3(1.0, 1.0, 1.0);
+#endif
     real cosTheta2 = sqrt(1.0 - sinTheta2);
 
     // First interface

com.unity.render-pipelines.high-definition/HDRP/Material/StackLit/StackLit.hlsl

             if (bsdfData.iridescenceMask > 0.0)
             {
                 preLightData.fresnelIridforCalculatingFGD = EvalIridescence(topIor, NdotV[0], bsdfData.iridescenceThickness, bsdfData.fresnel0);
-                f0forCalculatingFGD = lerp(bsdfData.fresnel0, preLightData.fresnelIridforCalculatingFGD, bsdfData.iridescenceMask);
+                f0forCalculatingFGD = lerp(f0forCalculatingFGD, preLightData.fresnelIridforCalculatingFGD, bsdfData.iridescenceMask);
             }
         }