Smart notifications are shown for any transaction done by the user. It can be a fund transfer or an ATM withdrawal or a bill payment completion message. The processes required for making your SMS smart happens locally on your mobile device. No message or information ever leaves your phone as part of this. All the information remains secure and it is processed offline on your device. It will never be used to identify you.
How to disable it?
Truecaller Settings > General > Smart Notifications.