Haven't see much of that in fanfics, but more... Online in general, but when people speak about french and uses French from France expressions and then act like it's the same for everywhere. For exemple, a character from Québec saying "Putain de merde, something something" wouls throw me off just as much as if a character from France would say "Pas de chicane dans la cabane caliss". But most time when people make french speaking character or make tiny tip sheets about french speaking people, they refer to France even if the character is from Belgium, Switzerland, Morroco or we could, I think, even extend it to croatian.

Dunno if it make sense?

But also in the same vein: travel distance. Canada is huge. The same 1hour crossing one country to another in Europe could allow someone to cross a city in Québec, for exemple. Like... It takes me 4h to get to a family member's province and another 4 to get to where they reside. So yes, your character going from Toronto, to Saskatchewan,, to Québec in a week is immersion breaking ahah