Android has a maximum number of notifications per app set by each manufacturer, most apps often display only the latest notification for each chat room.

This app uses the method of adding or grouping new notifications to old notifications to view all notifications, and copies the functions of the original notification as a new notification.

Once you run this app and complete settings, it runs in the background and you no longer need to run this app.

Notification deletion settings > When the app's automatic notification deletion function is turned off, notifications are not deleted even if the other person has deleted them.