Here is what COVID-19 policy says:
"Reservations for stays and Airbnb Experiences made after 14 March 2020 will not be covered under our extenuating circumstances policy, except where the guest or host is currently sick with COVID-19. COVID-19-related circumstances not covered include: transport disruptions and cancellations; travel advisories and restrictions; health advisories and quarantines; changes to applicable law; and other government mandates such as evacuation orders, border closures, prohibitions on short-term rentals, and lockdown requirements. The host’s cancellation policy will apply as usual.
Our extenuating circumstances policy is intended to protect guests and hosts from unforeseen circumstances that arise after booking. After the declaration of COVID-19 as a global pandemic by the World Health Organization, the extenuating circumstances policy no longer applies because COVID-19 and its consequences are no longer unforeseen or unexpected. Please remember to carefully review the host's cancellation policy when booking and consider choosing an option that provides flexibility."
So, according to COVID-19 EC policy, you are not entitled to full refund, if you booked in September.