diff --git a/src/EFCore/Metadata/Internal/InternalTypeBaseBuilder.cs b/src/EFCore/Metadata/Internal/InternalTypeBaseBuilder.cs
index b9ab85070bb..24333f89885 100644
--- a/src/EFCore/Metadata/Internal/InternalTypeBaseBuilder.cs
+++ b/src/EFCore/Metadata/Internal/InternalTypeBaseBuilder.cs
@@ -15,6 +15,9 @@ namespace Microsoft.EntityFrameworkCore.Metadata.Internal;
 public abstract class InternalTypeBaseBuilder : AnnotatableBuilder<TypeBase, InternalModelBuilder>,
     IConventionTypeBaseBuilder
 {
+    private static readonly bool UseOldBehavior34201 =
+        AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue34201", out var enabled34201) && enabled34201;
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
@@ -204,6 +207,7 @@ public static bool IsCompatible(MemberInfo? newMemberInfo, PropertyBase existing
                 || (memberInfo is PropertyInfo propertyInfo && propertyInfo.IsIndexerProperty()))
             {
                 if (existingProperty.GetTypeConfigurationSource() is ConfigurationSource existingTypeConfigurationSource
+                    && (typeConfigurationSource != null || UseOldBehavior34201)
                     && !typeConfigurationSource.Overrides(existingTypeConfigurationSource))
                 {
                     return null;
diff --git a/test/EFCore.Relational.Tests/Migrations/Internal/MigrationsModelDifferTest.cs b/test/EFCore.Relational.Tests/Migrations/Internal/MigrationsModelDifferTest.cs
index b0f732c5b56..aa91709aaec 100644
--- a/test/EFCore.Relational.Tests/Migrations/Internal/MigrationsModelDifferTest.cs
+++ b/test/EFCore.Relational.Tests/Migrations/Internal/MigrationsModelDifferTest.cs
@@ -8646,7 +8646,7 @@ public void Split_out_subtype_with_seed_data()
                         x.Property<string>("Name");
                         x.Property<int>("Discriminator");
 
-                        x.HasDiscriminator<int>("Discriminator")
+                        x.HasDiscriminator()
                             .HasValue(1)
                             .HasValue<Eagle>(2);