And yet it's still widely used out there in the anglosphere, such as in Australia where it's the official term for their indigenous population.
So while "Indigenous" may indeed be the preferred term for First Nations, Inuit and Métis people in Canada, it's hard to believe that it's offensive to the point of someone getting viciously slagged for innocently using it.
Very recently I spent some time abroad and had gatherings with people from all sorts of different countries, and at one point a person from a faraway land referred to Indigenous people as "American Indians" or something like that.
I could tell that a couple of bien-pensant types from the anglosphere almost threw up in their mouths a little bit upon hearing that.
As if we're all knowledgeable about the up-to-date terms to refer to every single group in every single country.
Oh yeah, and BTW:
https://americanindian.si.edu/