Hosts don't necessarily know all of the events that will bring in crowds.

So they book early for a guaranteed $x. Then if they see that market rates for nearby units rose to n*$x, it makes sense for them to cancel and rebook at that rate.

This happened to me in Boston. I was going to run the marathon and knew that I needed to book way ahead to ensure I could get a decent room, whether hotel or AirBNB. I booked an apartment in Back Bay. Two weeks later, the host realized it was going to be marathon weekend and tried to triple my price. When I refused his offer, he canceled me.

Fortunately, it was still early enough that I was able to book a hotel near the finish line. Unfortunately, that hotel ended up be the host of all of the press and press conferences when someone bombed the finish area.