Rocket.Chat recommends the following setting preferences to enable you to view any modified or removed messages.
Go to the Administration
Scroll down to Messages on the left-side menu.
Make sure to set your message preferences as follows:
Enable Allow Message Editing and Keep Per Message Editing History to see a history of all messages and not only the last edit made.
Disable Allow Message Deleting, otherwise, messages show only the message deleted status and you cannot see the complete message history.