I am trying to send a mobile push notification to my android device based on apex trigger, and I didn't see notification banner but in console I can see onNotification event fired and I can see my payload info. I have followed In react native app react-native-push-notification library, all changes are done as per the document mention here https://www.npmjs.com/package/react-native-push-notification.
updated MobilePushServiceDevice whenever user open the with token and service type
On FCM created the project and follow this document https://firebase.google.com/docs/cloud-messaging/android/client
Salesforce
create connected enable push notification added server key

   Messaging.PushNotification msg = new Messaging.PushNotification();
                
                Map<String, Object> androidPayload = new Map<String, Object>();
                Set<String> userSet = new Set<String>();
                androidPayload.put('title', idVSnickname.get(cbuId)+' assigned you a task');
                androidPayload.put('message', subject);
                androidPayload.put('parentId', str[4].trim());
                androidPayload.put('id', str[0].trim());
                androidPayload.put('objectName', 'Task');
                androidPayload.put('record', str[5]);
                userSet.add(accIdVSuserId.get(accId));
                msg.setPayload(androidPayload);
                msg.send('Mimit', userSet);