How to read deleted messages in any messenger on Android.
This can be done using the Notification History application.
To start recording notifications, go to system «Notification Access settings» and check «Notification History».
To stop the record, just uncheck these settings.
This method works for many instant messengers, however, it has its drawbacks: the notification history is deleted when the device is rebooted, and it is impossible to get the text of messages received before the logger was installed.