Please try to send Data Only Message instead of Notification Message. Also, refer to this link: https://firebase.google.com/docs/cloud-messaging/android/receive#handling_messages

What happen at android end if you send notification key in your payload then onMessageReceived() finction didn’t work, remove that notification key from payload and then try if key not present.

I have a php page and I want to send push notification to Android devices.

Here is a php code sample what is working:

<?php
function sendPushNotification($to, $data = array()){
    $fields = array('to' => '/topics/' .$to , 'notification' => $data);//, 'android_channel_id' => 'automento_szallitas');
    echo $fields['to'];
    echo $fields['notification'];
    
    //$headers = array('Authorization: key='.apiKey, 'Content-Type: application/json');
    $headers = array('Authorization: key=MY_SECRET_FCM_KEY', 'Content-Type: application/json');
    
    $url = 'https://fcm.googleapis.com/fcm/send';
    
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));
    $result = curl_exec($ch);
    curl_close($ch);
    return json_decode($result, true);
    echo "ok";
}
$data = array(
    'title' => 'title',
    'body' => 'body'
  );

sendPushNotification("myTopic", $data);
?>

I got the notification for the Android device, when the device screen is open. (Android 11 device) I enabled everything and turned of every energy save mode. I can get notification in few minutes from Firebase console whe a scree is locked till minutes. If I use the php code with a 10 minutes screen lock, de notification doesn’t arrive. I got it inmediatelly when I open the screen.
It seems the front end Android code is ok. I think there is a problem with the back end side php code but I haven’t a clue

***************** Anndroid *********************
Manifest:

        <service
        android_name=".services.AutomentoFirebaseMessagingService"
        android_directBootAware="true"
        android_exported="false">
        <intent-filter>
            <action android_name="com.google.firebase.MESSAGING_EVENT" />
        </intent-filter>
    </service>

Firebase service:

    override fun onMessageReceived(remoteMessage: RemoteMessage) {
    Log.d(TAG, "Topic message: " + remoteMessage.from)
    super.onMessageReceived(remoteMessage)

    val powerIntent = Intent(Intent.ACTION_POWER_CONNECTED)
    context?.sendBroadcast(powerIntent)

    wakeUpScreen()

    val intent = Intent(this, MainActivity::class.java)
    val pendingIntent = PendingIntent.getActivity(
        this,
        REQUEST_CODE, intent, PendingIntent.FLAG_ONE_SHOT
    )
    val channelId = getString(R.string.default_notification_channel_id)
    val notificationBuilder: NotificationCompat.Builder = NotificationCompat.Builder(this, channelId)
        .setSmallIcon(R.drawable.ic_rendeleseim_white_48)
        .setContentTitle(remoteMessage.notification!!.title)
        .setContentText(remoteMessage.notification!!.body)
        .setAutoCancel(true)
        .setContentIntent(pendingIntent)
        .setOngoing(true)
        .setPriority(NotificationCompat.PRIORITY_HIGH)
        .setLights(Color.RED, 500, 500)
    val notificationManager = getSystemService(NOTIFICATION_SERVICE) as NotificationManager

    val channel = NotificationChannel(
        channelId,
        "Pushnotification",
        NotificationManager.IMPORTANCE_HIGH,
    ).apply {
        lockscreenVisibility = Notification.VISIBILITY_PUBLIC
    }

    notificationManager.createNotificationChannel(channel)
    val notification = notificationBuilder.build()
    notification.flags = notification.flags or Notification.FLAG_INSISTENT
    notificationManager.notify(REQUEST_CODE, notification)
}

    private fun wakeUpScreen() {
    val powerManager = getSystemService(POWER_SERVICE) as PowerManager
    val isScreenOn: Boolean = powerManager.isInteractive
    if (!isScreenOn) {
        val wakeLock: PowerManager.WakeLock =
            (getSystemService(Context.POWER_SERVICE) as PowerManager).run {
                newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MentoMano::WakelockTag").apply {
                    acquire(1000)
                }
            }
    }

    val pm = baseContext.getSystemService(POWER_SERVICE) as PowerManager
    val isScreenOn2 = pm.isInteractive // check if screen is on

    if (!isScreenOn2) {
        val wl = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK or PowerManager.ACQUIRE_CAUSES_WAKEUP, "myApp:notificationLock")
        wl.acquire(3000) //set your time in milliseconds
    }
}

    fun subscribeToTopic() {
    val userId = sharedPreferences?.getInt(Constants.SHARED_USER_ID, -1)
    if (userId != -1) {
        val topic = "user$userId"
        FirebaseMessaging.getInstance().subscribeToTopic(topic)
            .addOnCompleteListener { task ->
                if (task.isSuccessful) {
                    Log.d(TAG, "subscribeToTopic: sikeres feliratkozás $topic")
                    AutomentoController().updateToken(userId!!, topic)
                        .observeOn(AndroidSchedulers.mainThread())
                        .subscribe({ response ->
                            Log.d(TAG, "onCreate: token update success: ${response.success} | response: ${response.message}")
                        },{
                        })
                } else {
                    Log.d(TAG, "subscribeToTopic: hiba a feliratkozás során")
                }
            }
    }
}

Help please