FCM shows default message than custom message when app is not running

Question

Problem: My FCM code shows different messages to different cases:

Case 1: When app is running it shows the custom notification body

Case 2:

Answer 1

From the document

When app is in foreground the onMessageReceived always calls.

When app is in background the onMessageReceived will be called when the payload only has the data property (it doesn't exist the notification property).

Hope it helps!