I create and manage websites, and have had a few owners with this same issue. Its not anything that Air bnb did or didn't do. Its your listing.. let me explain. Google implented a new search algorithm that changes how search results come up. It searches for listings with new content and pushes those to the top of the search results.
So, how does this affect you as a owner? You probably loaded your listing and your rates at the beginning of the year, like the rest of us and other than possibly going into to do a rate adjustment, you don't do a lot on the site. To google that shows a site that has no new content, therefore, it drops to the bottom of the search results. It does the same thing to any website, not just Air bnb, where the content is not "fresh".
So how do you fix it? Its a matter of loading new content on your site continously... while that sounds overwhelming - it is not.
Google only detects that there was activity on the site, not what was done. So what i have the people whose websites I built do is go in and change a sentence in the write up - re- word it - or change one of the photos. If you really love the content that you currently have, you can go it and change it, then wait an hour and go back in and change it back.
Google will detect that as new content being added/updated and it will push your listing back up to the top of the search results.
You will have to do it every couple of weeks for a couple of months to get you back to the top of the search results but it does work. You have to continue to do it to stay at the top.
Does that make sense? 🙂