As I mentioned earlier at threads addressing similar situations, I was able to get a one-time exception as BA did not fly to Istanbul for 8 months straight due to Turkey imposing 14 days of government imposed quarantine for UK arrivals during the Kent variant and UK red-listing Turkey for the spring/summer period in 2021.

In my claim, I explained the situation with one sentence and wrote the information of 5-6 BA flights that were cancelled including the route, the PNR and the date.

If the OP is located in Toronto, BA flew to Toronto for at least the previous 8 months as I know someone who flew BA to Toronto last October and Canada relaxed their border restrictions last year.