Payment reversal notifications are used to inform Google's risk engine and the merchant that the integrator has incurred bad debt.
Typically, the integrator will represent this as a chargeback. However, Google does not accept chargebacks with this specification. That said, Google still wants a signal to help understand how money is flowing, fraud rings are forming, etc.
In order to do that, Google provides two method calls the integrator can use to inform us of inquiries and disputes.
method informs Google that an inquiry has started between the user and the
method informs Google that a dispute has been finalized and a portion
or all of the original transaction has been reversed. A dispute can reference
an inquiry, or can be called independently of any inquiry.
It's critical to note that there is no monetary impact to any of the calls above.