I'm indigenous Canadian and the weird part for me is that I know the opposite of this. I have family and friends from Six Nations in southern Ontario. They are Mohawk and I know a couple of war veterans who were part of the Canadian forces in WWII.
When they came back there was so much normalized racism that they couldn't identify as indigenous because they would be excluded from jobs and even owning or running businesses. As identified indigenous people they were given a hard time for employment, banking and buying or owning real estate.
So a lot of them identified themselves as Italian Canadians in order to get by.