diff --git a/services/core/java/com/android/server/notification/NotificationManagerService.java b/services/core/java/com/android/server/notification/NotificationManagerService.java
index 3dd2f1e..42ec1c3 100755
--- a/services/core/java/com/android/server/notification/NotificationManagerService.java
+++ b/services/core/java/com/android/server/notification/NotificationManagerService.java
@@ -245,7 +245,6 @@
 import android.os.DeviceIdleManager;
 import android.os.Environment;
 import android.os.Handler;
-import android.os.HandlerExecutor;
 import android.os.HandlerThread;
 import android.os.IBinder;
 import android.os.IInterface;
@@ -2038,19 +2037,21 @@
                     mSnoozeHelper.clearData(userHandle);
                 }
             } else if (action.equals(Intent.ACTION_USER_SWITCHED)) {
-                final int userId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, USER_NULL);
-                mUserProfiles.updateCache(context);
-                if (!mUserProfiles.isProfileUser(userId, context)) {
-                    // reload per-user settings
-                    mSettingsObserver.update(null);
-                    // Refresh managed services
-                    mConditionProviders.onUserSwitched(userId);
-                    mListeners.onUserSwitched(userId);
-                    mZenModeHelper.onUserSwitched(userId);
-                    mPreferencesHelper.syncChannelsBypassingDnd();
+                if (!Flags.useSsmUserSwitchSignal()) {
+                    final int userId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, USER_NULL);
+                    mUserProfiles.updateCache(context);
+                    if (!mUserProfiles.isProfileUser(userId, context)) {
+                        // reload per-user settings
+                        mSettingsObserver.update(null);
+                        // Refresh managed services
+                        mConditionProviders.onUserSwitched(userId);
+                        mListeners.onUserSwitched(userId);
+                        mZenModeHelper.onUserSwitched(userId);
+                        mPreferencesHelper.syncChannelsBypassingDnd();
+                    }
+                    // assistant is the only thing that cares about managed profiles specifically
+                    mAssistants.onUserSwitched(userId);
                 }
-                // assistant is the only thing that cares about managed profiles specifically
-                mAssistants.onUserSwitched(userId);
             } else if (action.equals(Intent.ACTION_USER_ADDED)) {
                 final int userId = intent.getIntExtra(Intent.EXTRA_USER_HANDLE, USER_NULL);
                 if (userId != USER_NULL) {
@@ -2570,7 +2571,9 @@
         // calling onDestroy()
         IntentFilter filter = new IntentFilter();
         filter.addAction(Intent.ACTION_USER_STOPPED);
-        filter.addAction(Intent.ACTION_USER_SWITCHED);
+        if (!Flags.useSsmUserSwitchSignal()) {
+            filter.addAction(Intent.ACTION_USER_SWITCHED);
+        }
         filter.addAction(Intent.ACTION_USER_ADDED);
         filter.addAction(Intent.ACTION_USER_REMOVED);
         filter.addAction(Intent.ACTION_USER_UNLOCKED);
@@ -2966,6 +2969,26 @@
     }
 
     @Override
+    public void onUserSwitching(@Nullable TargetUser from, @NonNull TargetUser to) {
+        if (!Flags.useSsmUserSwitchSignal()) {
+            return;
+        }
+        final int userId = to.getUserIdentifier();
+        mUserProfiles.updateCache(getContext());
+        if (!mUserProfiles.isProfileUser(userId, getContext())) {
+            // reload per-user settings
+            mSettingsObserver.update(null);
+            // Refresh managed services
+            mConditionProviders.onUserSwitched(userId);
+            mListeners.onUserSwitched(userId);
+            mZenModeHelper.onUserSwitched(userId);
+            mPreferencesHelper.syncChannelsBypassingDnd();
+        }
+        // assistant is the only thing that cares about managed profiles specifically
+        mAssistants.onUserSwitched(userId);
+    }
+
+    @Override
     public void onUserStopping(@NonNull TargetUser user) {
         mHandler.post(() -> {
             Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "notifHistoryStopUser");
diff --git a/services/core/java/com/android/server/notification/flags.aconfig b/services/core/java/com/android/server/notification/flags.aconfig
index af3db6c..9dcca49 100644
--- a/services/core/java/com/android/server/notification/flags.aconfig
+++ b/services/core/java/com/android/server/notification/flags.aconfig
@@ -128,3 +128,10 @@
   description: "Adds an IPCDataCache for notification channel/group lookups"
   bug: "331677193"
 }
+
+flag {
+  name: "use_ssm_user_switch_signal"
+  namespace: "systemui"
+  description: "This flag controls which signal is used to handle a user switch system event"
+  bug: "337077643"
+}
diff --git a/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java b/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
index b366f92..5e2fe6a 100755
--- a/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
+++ b/services/tests/uiservicestests/src/com/android/server/notification/NotificationManagerServiceTest.java
@@ -341,7 +341,6 @@
 import java.io.FileOutputStream;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CountDownLatch;
@@ -503,7 +502,7 @@
     @Mock
     MultiRateLimiter mToastRateLimiter;
     BroadcastReceiver mPackageIntentReceiver;
-    BroadcastReceiver mUserSwitchIntentReceiver;
+    BroadcastReceiver mUserIntentReceiver;
     BroadcastReceiver mNotificationTimeoutReceiver;
     NotificationRecordLoggerFake mNotificationRecordLogger = new NotificationRecordLoggerFake();
     TestableNotificationManagerService.StrongAuthTrackerFake mStrongAuthTracker;
@@ -802,11 +801,13 @@
                     && filter.hasAction(Intent.ACTION_PACKAGES_SUSPENDED)) {
                 mPackageIntentReceiver = broadcastReceivers.get(i);
             }
-            if (filter.hasAction(Intent.ACTION_USER_SWITCHED)) {
+            if (filter.hasAction(Intent.ACTION_USER_SWITCHED)
+                    || filter.hasAction(Intent.ACTION_PROFILE_UNAVAILABLE)
+                    || filter.hasAction(Intent.ACTION_MANAGED_PROFILE_UNAVAILABLE)) {
                 // There may be multiple receivers, get the NMS one
                 if (broadcastReceivers.get(i).toString().contains(
                         NotificationManagerService.class.getName())) {
-                    mUserSwitchIntentReceiver = broadcastReceivers.get(i);
+                    mUserIntentReceiver = broadcastReceivers.get(i);
                 }
             }
             if (filter.hasAction(ACTION_NOTIFICATION_TIMEOUT)
@@ -815,7 +816,7 @@
             }
         }
         assertNotNull("package intent receiver should exist", mPackageIntentReceiver);
-        assertNotNull("User-switch receiver should exist", mUserSwitchIntentReceiver);
+        assertNotNull("User receiver should exist", mUserIntentReceiver);
         if (!Flags.allNotifsNeedTtl()) {
             assertNotNull("Notification timeout receiver should exist",
                     mNotificationTimeoutReceiver);
@@ -976,7 +977,7 @@
     private void simulateProfileAvailabilityActions(String intentAction) {
         final Intent intent = new Intent(intentAction);
         intent.putExtra(Intent.EXTRA_USER_HANDLE, TEST_PROFILE_USERHANDLE);
-        mUserSwitchIntentReceiver.onReceive(mContext, intent);
+        mUserIntentReceiver.onReceive(mContext, intent);
     }
 
     private ArrayMap<Boolean, ArrayList<ComponentName>> generateResetComponentValues() {
@@ -14482,13 +14483,33 @@
     }
 
     @Test
+    @EnableFlags(Flags.FLAG_USE_SSM_USER_SWITCH_SIGNAL)
     public void onUserSwitched_updatesZenModeAndChannelsBypassingDnd() {
+        mService.mZenModeHelper = mock(ZenModeHelper.class);
+        mService.setPreferencesHelper(mPreferencesHelper);
+
+        UserInfo prevUser = new UserInfo();
+        prevUser.id = 10;
+        UserInfo newUser = new UserInfo();
+        newUser.id = 20;
+
+        mService.onUserSwitching(new TargetUser(prevUser), new TargetUser(newUser));
+
+        InOrder inOrder = inOrder(mPreferencesHelper, mService.mZenModeHelper);
+        inOrder.verify(mService.mZenModeHelper).onUserSwitched(eq(20));
+        inOrder.verify(mPreferencesHelper).syncChannelsBypassingDnd();
+        inOrder.verifyNoMoreInteractions();
+    }
+
+    @Test
+    @DisableFlags(Flags.FLAG_USE_SSM_USER_SWITCH_SIGNAL)
+    public void onUserSwitched_broadcast_updatesZenModeAndChannelsBypassingDnd() {
         Intent intent = new Intent(Intent.ACTION_USER_SWITCHED);
         intent.putExtra(Intent.EXTRA_USER_HANDLE, 20);
         mService.mZenModeHelper = mock(ZenModeHelper.class);
         mService.setPreferencesHelper(mPreferencesHelper);
 
-        mUserSwitchIntentReceiver.onReceive(mContext, intent);
+        mUserIntentReceiver.onReceive(mContext, intent);
 
         InOrder inOrder = inOrder(mPreferencesHelper, mService.mZenModeHelper);
         inOrder.verify(mService.mZenModeHelper).onUserSwitched(eq(20));