I think it's because they don't have their own accents. Black Canadians talk exactly like white Canadians down to their enunciation and even voice. Every other diaspora, you can tell the speaking distinction between the black population and other ethnicitys. It's weird, the Weeknd sounds like a black man on records but when you hear him speak, he sounds like Kermit. And we all know how Drake actually sounds like.
Another reason we might think they're weird is because they don't have a culture that was homegrown in Canada that they can claim as there own. Alot of what they do culture wise are borrowed from their parents homeland and different American urban cities. So they might not come off too authentic.
btw, this doesn't pertain to ALL black Canadians
edit:
@I Really Mean It kind of touched on it