I notice this a lot in Canada and the US. I think it's a weird internalization of the fact that these countries are made up of colonizers and people the colonizers brought in to do their dirty work for them.

Let me preface this by saying I'm white, and I lived in pretty much the same place until I was about 20. Most of my friends and acquaintances were also white and also born and raised in the area. My take on this is based on that lived experience. I am very aware that this question can take on very dark racist tones depending on the context.

"Where are you from" in a lot of cases doesn't mean "you look different or you talk different," it means "where did your ancestors come from"? When people ask, or volunteer this information, they're talking about that family history. This is how you get people from Alberta with four generations of family history in Alberta claiming that they're "a quarter German, a quarter Italian, an eighth Irish, and an eighth English", and that's the type of answer they expect when they ask a white or white-passing person this question.