@Clarence1 well, as far as I know, Airbnb does not have 1099, as It does not consider you a contractor. You can go to Payouts and download the year(s) in question and pull out your income from that. I am guessing that Palm Springs charges Airbnb Guest or Resort taxes and that is how they found out you have a business. And they probably want you to pay Gross Receipts Taxes on your income. If you do not already have a business license, then you might apply for one.
I download the income from Airbnb to a spreadsheet and then back out the taxes from it, as I include the Gross Receipts Tax in the amount paid to me. I suspect that you will be doing something similar. But do not wait long, as you could end up with penalties and interest, if that is why they are inquiring now!