Reject reservations with failed payment
If a payment is declined by the payment processor, the reservation should not be accepted and cancelled to keep the calendar available
They system already rejects reservations with failed payments, with the exception of particular cases on VRBO and Booking.com: for Booking.com, their platform is initially made for hotels and they consider that a reservation is valid even if the payment is not yet received. For VRBO, in the case of 3DS2 security validation failing (case that mostly applies to Europe), a reservation will be ok'ed and a payment link will the sent to the guest to pay immediately on Hostfully. Note that this latter case for VRBO is about to be handled and this flow will work as expected.