iOS purchase dialog box pop again on UserCancelled. Anyone met this problem before?

I printed the log and the button and other functions in the class were called once. I almost follow what the tutorial does. I tried to search on google but it seems that I am the only one who have this problem. May be I missed something or did something wrong? And the document did tell what I could do in OnPurchaseFailed(). The parameters it offers don't seem to do anything.
Or is it a normal behavior? I am using 2019.3.1f1. Any input is appreciated. Thank you.

Code (CSharp):

1. public class Purchaser : MonoBehaviour, IStoreListener
2. {
3.  
4.     public static IStoreController m_StoreController;
5.     public static IExtensionProvider m_StoreExtensionProvider;
6.  
7.  
8. private void Awake()
9.     {
10.    
11.         var builder = ConfigurationBuilder.Instance(StandardPurchasingModule.Instance());
12.         builder.AddProduct(kProductIDNonConsumable, ProductType.NonConsumable);
13.         UnityPurchasing.Initialize(this, builder);
14.       }
15.  
16. public void InitializePurchasing()
17.     {
18.      
19.         if (IsInitialized())
20.         {
21.        
22.             return;
23.         }
24.         var builder =ConfigurationBuilder.Instance(StandardPurchasingModule.Instance());
25.         builder.AddProduct(kProductIDNonConsumable, ProductType.NonConsumable);
26.         UnityPurchasing.Initialize(this, builder);
27.      
28.     }
29.  
30. public bool IsInitialized()
31.     {
32.         Product product =m_StoreController.products.WithID(kProductIDNonConsumable);
33.  
34.         if (product != null && product.availableToPurchase)
35.         {
36.          
37.             m_StoreController.InitiatePurchase(product);
38.  
39.         }
40.             return m_StoreController != null && m_StoreExtensionProvider != null;
41.     }
42.  
43. public void BuyNonConsumable()
44.     {
45.       //OnClick calls this function
46.        BuyProductID(kProductIDNonConsumable);
47.    
48.        
49.     }
50. public void BuyProductID(string productId)
51.     {
52.  
53.         if (IsInitialized())
54.             {
55.                 Product product = m_StoreController.products.WithID(productId);
56.  
57.                 if (product != null && product.availableToPurchase)
58.                 {
59.                  
60.                     m_StoreController.InitiatePurchase(product);
61.                 }
62.                 else
63.                 {
64.                     Debug.Log("Product not found or not available for purchase!");
65.                 }
66.             }
67.             else
68.             {
69.                 Debug.Log("Not able to initialize the purchase.");
70.             }
71.         }
72.  
73. public void OnPurchaseFailed(Product i, PurchaseFailureReason p)
74.     {
75.         Debug.Log("Purchase failed " + p);
76.         if(p == PurchaseFailureReason.UserCancelled)
77.         {
78.             //I don't know what I can do to stop it from calling the dialog box again here!
79.         }
80.     }
81. public void OnInitialized(IStoreController controller, IExtensionProvider extensions)
82.     {
83.    
84.         m_StoreController = controller;
85.         m_StoreExtensionProvider = extensions;
86.         Product product = m_StoreController.products.WithID(kProductIDNonConsumable);
87.  
88.         if (product != null && product.availableToPurchase)
89.         {
90.                //I cache the order information to local storage here.
91.  
92.         }
93.     }
94. }

 

And here is the Xcode log between 2 Cancel taps. Sorry it's an AR app that I have to test it on physical devices.

Purchase failed UserCancelled

Purchaser:OnPurchaseFailed(Product, PurchaseFailureReason)

UnityEngine.Purchasing.JSONStore:OnPurchaseFailed(PurchaseFailureDescription, String)

System.Action:Invoke()

UnityEngine.Purchasing.Extension.UnityUtil:Update()


(Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 35)


-> applicationWillResignActive()

2020-04-18 16:56:49.155451+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.155862+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.156196+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.156716+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.156788+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.202135+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.202228+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.206324+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.206739+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:49.334475+0100 helloworldar[25948:6164156] Could not signal service com.apple.WebKit.WebContent: 113: Could not find specified service

2020-04-18 16:56:49.336556+0100 helloworldar[25948:6164156] Could not signal service com.apple.WebKit.Networking: 113: Could not find specified service

2020-04-18 16:56:50.807424+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:50.807736+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:50.894903+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:50.895046+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:50.895140+0100 helloworldar[25948:6164156] UnityIAP: UpdatedTransactions

2020-04-18 16:56:50.895220+0100 helloworldar[25948:6164156] UnityIAP: PurchaseFailed: 2

-> applicationDidBecomeActive()

2020-04-18 16:56:51.233611+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:51.234731+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:51.235045+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

2020-04-18 16:56:51.235896+0100 helloworldar[25948:6164156] [Process] kill() returned unexpected error 1

onPurchaseFailedEvent({0}): helloworldar.premium

UnityEngine.Purchasing.PurchasingManager:OnPurchaseFailed(PurchaseFailureDescription)

UnityEngine.Purchasing.JSONStore:OnPurchaseFailed(PurchaseFailureDescription, String)

System.Action:Invoke()

UnityEngine.Purchasing.Extension.UnityUtil:Update()


(Filename: ./Runtime/Export/Debug/Debug.bindings.h Line: 35)


Purchase failed UserCancelled

 

Update: It looks like that it's an iOS problem. After updating my iPhone7 to 13.4.1. The bug just went away.