@Kasey45 Yes, this is on Airbnb. Airbnb should most definitely be supporting you in contacting alternate Airbnb listings and possibly negotiating a rate for rate replacement option - and definitely covering a portion of the difference given the significance of the cancellation for you.
I'm very sorry that this has happened to you, but yes, during a massive global crisis like a pandemic, the sudden need to sell a property (or possibly even an unexpected 'off market' offer on the property which has reached the owner at a difficult time in their lives) is certainly a possibility. The pandemic has caused job/ income losses, health issues (and associated costs), and massive reductions in travel and Airbnb income, causing massive mortgage and financial stress to many, including those who have had multiple 'safety nets' in place that have all unforeseeably blown at once due to the previously unimaginable global pandemic.
It's devastating for you, but you really must consider that the host may have buckled under the financial pressures of COVID19, and been forced to sell unexpectedly.
Airbnb must step up and provide support for you. Given the huge amount of money they tricked guests out of and lined their own pockets with when they instigated millions of automatic cancellations last year, telling guests they could only get travel vouchers or half of their reservation amount, while paying hosts nothing, they owe guests such as yourself support.
NB: when Airbnb automatically cancelled millions of bookings without consultation or care as to whether an area was impacted by COVID19, guests desperate for some cash refund of any kind accepted Airbnb's offer of half of the value of their booking, and many of those that chose travel credit will never have the opportunity to use it before expiry, given their own changing personal situation. Either way, hosts suddenly received nothing, and Airbnb pocketed huge amounts of money at guest's expense.
I realise that this will be an unpopular and uncomfortable position to highlight, but for those that still have jobs, their health, and the funds to travel, without any Government travel restrictions in place, please be mindful that this is a luxury many do not have, and that the owners of homes you may be staying in may be under massive "life happening" strain from a number of angles right now, which they would never have foreseen coming in a million years. We're in the middle of a global pandemic and many are hanging on by the skin of their teeth.