@Kelly1227
Best to take the matter into your own hands.
Telling the guest to contact airbnb still means that it bounces all the way back to you to make a decision. You might find an airbnb rep phoning you pressurizing you to do ''the right thing ™''
Unless it falls into some EC or covid policy, it's you that decides not airbnb.
If the guest cancels ,and it's easy as pie to hit the cancel button as a guest, under the long term cancellation policy, you are due to receive the first payment ( of thirty days) and airbnb scoop the service fee as ever.
You can tell the guest ; 1 - too bad, my regrets but that's what you agreed to at booking and you can't change the goalposts 2 - you can give a refund of your portion or part thereof 3 - you might say, no refund but if someone else books during the first 30 days of the cancelled trip you would refund in the future pro-rata 4 - too bad, but how about a discount in future?. Make a decision, now.
I'd refer the guest to contact airbnb if they are inclined to discuss the service fee portion.