Hi @Julia2882,
As long the host accepts the guest's alteration date request, that is no penalty on the host side.
https://www.airbnb.com/help/article/1504/how-does-it-work-if-a-guest-wants-to-change-their-reservati...
Nevertheless, if the payment has done to the hosting account, the guest requests to shorten the reservation date, and the host accepted. Airbnb will deduct the host's future payout recording to the check-out early date.
Both guests and hosts can decline an alteration request to keep a reservation as-is.
Guests and hosts may send an alteration request if they'd like to make changes to a confirmed reservation.
If you accept, changes to the confirmed reservation will be reflected immediately.
The safest way to secure your payment, do not accept the alteration request; advise the guest is necessary to make the cancellation by the guest side rather than shorten down the reservation date.
https://www.airbnb.com/help/article/2389/can-i-decline-an-alteration-request