Sometimes information about a transaction (like the name, date, or amount) can change for many reasons, and detecting these changes can be difficult via the /transactions/get endpoint. A request needs to be made to the /transactions/get endpoint to pull the latest information and then would need to be compared with the stored information from previous requests. The DEFAULT_UPDATE, which signals a transaction update for an Item and provides the number of new transactions, does not provide insight to such changes of transaction information. The TRANSACTIONS_WEBHOOK will signal when transaction(s) for an Item are deleted.
The /transactions/sync endpoint does provide insight to when transaction information changes and lists any transactions with modified information in the updated object of the response. When transactions are deleted they are listed in the removed object of the response and the same for any newly added transactions. To be alerted when there is new, updated, or deleted data, listen for the SYNC_UPDATES_AVAILABLE webhook.