@Laura4540 You say "my host should have kept me informed about the rapid evolution leading to a general lockdown."
-I'm not sure I agree with that; I think it's your OWN responsibility to keep abreast of anything that will disrupt your plans when travelling.
-It could be argued, that booking flights/accommodation during a pandemic is a known risk, and if you're not prepared to accept the consequences of events being cancelled, don't book!!
Secondly, I don't know what's wrong with your host asking YOU to cancel? If the host had done a normal cancellation, Airbnb would have charged her a $100 penalty, and stopped her Superhost status, so hosts do not like cancelling!
Personally, I WOULD refund a guest in those circumstances, and 2 days ago issued a full refund to a guest who KNEW she was booking illegally, but instant booked anyway. But I guess your host would argue she is just upholding her cancellation policy which you effectively agreed to when you booked?