Change

Assets/MobileARTemplateAssets/UI/Scripts/CutoutMaskUI.cs

@@ -0,0 +1,21 @@
+using UnityEngine;
+using UnityEngine.UI;
+using UnityEngine.Rendering;
+
+namespace Unity.AR.Companion.Mobile
+{
+    class CutoutMaskUI : Image
+    {
+        static readonly int k_StencilComp = Shader.PropertyToID("_StencilComp");
+
+        public override Material materialForRendering
+        {
+            get
+            {
+                var renderingMaterial = new Material(base.materialForRendering);
+                renderingMaterial.SetInt(k_StencilComp, (int)CompareFunction.NotEqual);
+                return renderingMaterial;
+            }
+        }
+    }
+}

Assets/MobileARTemplateAssets/UI/Scripts/CutoutMaskUI.cs.meta

@@ -0,0 +1,11 @@
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+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
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