For anyone wondering this is at current time Provincially regulated.
Some provinces have regulations that require a person’s written consent if an insurance agreement restricts access to their pharmacy of choice, including Ontario. But according to the Ontario College of Pharmacists, when it comes to preferred provider contracts, “consent is given by the [patient] when they opt-in or enrol for benefits.”
The only province in Canada where these kinds of exclusivity deals are illegal is in Quebec. The province’s Bill 92 prohibits preferred pharmacy arrangements between pharmacies and insurance providers.