I have found this:

https://www.routesonline.com/news/29...ng-passengers/

Contradictory to a press release cited in posts #31 and #41, it says:

Passengers flying to Canada must download the ArriveCAN app 72 hours before departure. Once a passenger clears customs, he or she will get a message sent to the app within 15 minutes letting them know they have been randomly selected for testing. The app will help passengers find a testing site and book an appointment

IMHO this sounds much more serious than the old testing-regime they had before the tests were paused. You can hardly pretend you didn't get the notification in the ArriveCAN app when the app was necessary to make it into Canada at all. It worked that far, and then, all of a sudden, the app has allegedly failed once you've been selected for the test? No one will believe that. It seems they've learnt their lesson.