We should call them Qubecois.
“Quebecers” is absolutely the worst demonym I’ve ever had the misfortune of hearing.
I’d honestly rather use “Quebecans” or “Quebecinites” than “Quebecers”. That being said, I’m francophone so I just say “québécois et québécoises”.
In Ontario I’ve generally heard and used “Québécois” and don’t really hear Quebecers often. Weird that the Montréal CityNews outlet is using Quebecers of all places.
In my mind Québécois is a sign of respect, while Quebecers is dismissive, and I can’t explain why I think that way.