These notifications are sent even if there was no actual change of bank details i.e. in cases when the screen was accessed by a user and the existing values such as bank account number, sort code have been saved without any update.
It is recommended to rely on the audit report rather than on the one showing the notifications. The audit report shows changes only when a new value is entered which means that if the same value is entered/saved the audit does not treat this as an update/change. However, in such cases, the system sends the notification that the bank details were updated.
We provide guidance if you are unsure how to generate a bank details audit report.