@Jerome59 - it's a test feature that Airbnb is trying out. Essentially, if the guest books far enough in advance, they need to pay half now and then pay the remainder closer to the date. The guest is still held to the cancellation policy of the host property.
https://www.fastcompany.com/40410787/airbnb-is-quietly-testing-flexible-payment-options-for-guests.
If your guests click the ""Learn more" next to this option they will be told: "Pay less upfront
When you use a credit card or PayPal to book an eligible reservation, you’ll have the option to pay part of the total now, and the remaining amount closer to the check-in date. You won’t be charged additional fees for choosing this option.
What happens on the day of my second payment? No action is required from you. On the second payment due date, we’ll automatically charge the payment method you used to reserve the booking for the initial payment. If there are any problems with this payment, we’ll send you an email update. If we are unable to collect the remaining balance, we will cancel the reservation on your behalf and you will be refunded based on the host’s cancellation policy."
