No, not new at all. And not just at YYZ. Passport check at the gate (some agents will accept Nexus card, others won’t) is transportation regulations for any flight to or from Canada - from any country.

It’s pretty old - this has been a requirement as part of the changes after 9/11. Note many other jurisdictions don’t require it, but many airlines to do it anyway to protect themselves (if they carry a pax to international destination and they don’t have proper entry docs - airline will be forced to return pax home on their next flight and can get fined - they obviously want to make sure there is little risk of that happening).