This is definitely NOT true in Toronto, which is certainly a "hot market":Certainly rentals (even before the pandemic) were not being rented right away but the listing time in padmapper.com was usually not long (less than a month). I agree there's a change in the rental market, but in hot markets, there are no downward pressure on rents where there are still increasing returnees and interprovincial migrants.
https://nowtoronto.com/news/toronto-rent-dropped-as-much-as-22-per-cent-downtown