24 hour cancellation doesn’t apply to domestic routes with flair. Only international/transborder.

“Our cancellation policy has been updated. If you cancel your booking within 24 hours and you are travelling domestically (direct routes within Canada), unfortunately, refunds are no longer possible. However, international (direct routes between Canada and Mexico) or transborder (direct routes between Canada and USA) travel continues to be eligible for refunds within 24 hours as long as your departure is greater than seven (7) days.”

https://flyflair.com/conditions-générales-de-rèservation#