@Jill1024 What do you mean, "cancelling before they pay a deposit"?
If a guest books using Instant Book, they get charged by Airbnb instantly.
If they send a Booking Request, which the host accepts, they get charged by Airbnb instantly.
If they send an Inquiry, which the host pre-approves, they then have to go on to book, and most don't- they're just tire-kickers and may have sent out 20 Inquiries.
Nor do guests pay a "deposit". They are either charged the full amount when they book, or in some circumstances they can opt to pay half up front and half a week or so before check-in.
Can you be more specific as to what you are talking about??