The cardholder does not have to call into question or dispute the entire amount as displayed on his or her credit card statement. Often, only the tip amount or even only the tip amount itself is disputed by the cardholder.
In addition, in many cases Toast absorbs a portion of the chargeback, making the amount debited from the merchant lower than that indicated in the notification.
Also, in the case where the card originates from a foreign country, currency exchange rates apply. These exchange rates are usually applied based on when the dispute was created, not when the transaction occurred.
Lastly, cardholder bank fees could skew the amounts even further.
Toast often cannot provide details into the amounts as listed in the draft retrieval request and chargeback notifications, as only the cardholder will know the details.