@Catrin6 @Kate867 If you want to make the open dates on your listings' calendars available to people in crisis (including, but not limited to, Ukrainian refugees) follow this link: https://www.airbnb.com/for-airbnb-org/how-to-host
To the best of my knowledge, Airbnb is not exempting hosts from cancellation penalties for hosts who want to switch from a normal booking to an Open Home, so that is really not a workable solution. It's not really in the spirit of charity to screw over your existing guests to help out hypothetical ones. But apart from offering accommodation, there are many other ways you can volunteer your time and resources to support refugees in and beyond your community. And of course there's nothing stopping you from donating the proceeds from your committed bookings to charities that are better able to maximize the impact of every pound.