fix: Resolved the tag-related issue (#2090)

Author: Prekshith-Microsoft

infra/main.bicep

@@ -371,6 +371,8 @@ var allTags = union(
   tags
 )
 
+var existingTags = resourceGroup().tags ?? {}
+
 @description('Optional. Created by user name.')
 param createdBy string = contains(deployer(), 'userPrincipalName')
   ? split(deployer().userPrincipalName, '@')[0]
@@ -379,12 +381,14 @@ param createdBy string = contains(deployer(), 'userPrincipalName')
 resource resourceGroupTags 'Microsoft.Resources/tags@2025-04-01' = {
   name: 'default'
   properties: {
-    tags: {
-      ...resourceGroup().tags
-      ...allTags
-      TemplateName: 'CWYD'
-      CreatedBy: createdBy
-    }
+    tags: union(
+      existingTags,
+      allTags,
+      {
+        TemplateName: 'CWYD'
+        CreatedBy: createdBy
+      }
+    )
   }
 }