I have no idea of the real reason the host cancelled and I can't remember when exactly Scotland came out of lockdown but this time last year, we were in a very different situation with COVID, travel restrictions etc. and many hosts had lost most of their bookings in the months preceding. I still have COVID related cancellations as late as December 2021.
So, it wouldn't surprise me if prices back then were very low. Now a lot of people are travelling. When I travelled a couple of weeks ago, I couldn't believe the queues at the airport. Plus August is probably the most popular time to visit Edinburgh with the International and Fringe festivals taking place that month. If prices have just gone back to 'normal', it wouldn't surprise me if they are three times what @Debbie1054 booked the airbnb for.
That's not to excuse the host if that's the reason he/she cancelled, i.e. to get a higher priced booking (Airbnb might block the dates, but that's not to say the listing isn't also on other platforms), but I think it unlikely that anyone could now find cheap accommodation in Edinburgh in August. I may be wrong though. When I went to the Fringe, I stayed with friends.