diff --git a/e2e_test/source_inline/kafka/protobuf/alter_source_shared.slt b/e2e_test/source_inline/kafka/protobuf/alter_source_shared.slt
index 5301eda7679b1..658d4fa95c6a0 100644
--- a/e2e_test/source_inline/kafka/protobuf/alter_source_shared.slt
+++ b/e2e_test/source_inline/kafka/protobuf/alter_source_shared.slt
@@ -26,30 +26,21 @@ CREATE MATERIALIZED VIEW mv_user AS SELECT * FROM src_user;
 statement ok
 CREATE MATERIALIZED VIEW mv_user_2 AS SELECT * FROM src_user;
 
-statement ok
-CREATE TABLE t_user WITH (
-    ${RISEDEV_KAFKA_WITH_OPTIONS_COMMON},
-    topic = 'pb_alter_source_shared_test',
-    scan.startup.mode = 'earliest'
-)
-FORMAT PLAIN ENCODE PROTOBUF(
-    schema.registry = '${RISEDEV_SCHEMA_REGISTRY_URL}',
-    message = 'test.User'
-);
-
 # age is new field
 statement error
 SELECT age FROM mv_user;
 
-statement error
-SELECT age FROM t_user;
-
 # Push more events with extended fields
 system ok
 python3 e2e_test/source_inline/kafka/protobuf/pb.py "${RISEDEV_KAFKA_BOOTSTRAP_SERVERS}" "${RISEDEV_SCHEMA_REGISTRY_URL}" "pb_alter_source_shared_test" 5 user_with_more_fields
 
 sleep 5s
 
+
+# set session variable shouldn't affect existing source.
+statement ok
+set streaming_use_shared_source to false;
+
 # Refresh source schema
 statement ok
 ALTER SOURCE src_user REFRESH SCHEMA;
diff --git a/src/frontend/src/handler/alter_source_with_sr.rs b/src/frontend/src/handler/alter_source_with_sr.rs
index 05548351492b9..196d4a7eaf39e 100644
--- a/src/frontend/src/handler/alter_source_with_sr.rs
+++ b/src/frontend/src/handler/alter_source_with_sr.rs
@@ -168,7 +168,7 @@ pub async fn refresh_sr_and_get_columns_diff(
         session,
         format_encode,
         Either::Right(&with_properties),
-        CreateSourceType::from_with_properties(session, &with_properties),
+        CreateSourceType::for_replace(original_source),
     )
     .await?
     else {
diff --git a/src/frontend/src/handler/create_source.rs b/src/frontend/src/handler/create_source.rs
index 2981a96423edf..91abf9acf6c99 100644
--- a/src/frontend/src/handler/create_source.rs
+++ b/src/frontend/src/handler/create_source.rs
@@ -152,7 +152,8 @@ pub enum CreateSourceType {
 }
 
 impl CreateSourceType {
-    pub fn from_with_properties(
+    /// Note: shouldn't be used for `ALTER SOURCE`, since session variables should not affect existing source. We should respect the original type instead.
+    pub fn for_newly_created(
         session: &SessionImpl,
         with_properties: &impl WithPropertiesExt,
     ) -> Self {
@@ -172,6 +173,16 @@ impl CreateSourceType {
         }
     }
 
+    pub fn for_replace(catalog: &SourceCatalog) -> Self {
+        if !catalog.info.is_shared() {
+            CreateSourceType::NonShared
+        } else if catalog.with_properties.is_shareable_cdc_connector() {
+            CreateSourceType::SharedCdc
+        } else {
+            CreateSourceType::SharedNonCdc
+        }
+    }
+
     pub fn is_shared(&self) -> bool {
         matches!(
             self,
@@ -818,7 +829,7 @@ pub async fn handle_create_source(
     let format_encode = stmt.format_encode.into_v2_with_warning();
     let with_properties = bind_connector_props(&handler_args, &format_encode, true)?;
 
-    let create_source_type = CreateSourceType::from_with_properties(&session, &*with_properties);
+    let create_source_type = CreateSourceType::for_newly_created(&session, &*with_properties);
     let (columns_from_resolve_source, source_info) = bind_columns_from_source(
         &session,
         &format_encode,