A US poster of Mexican origin explained that on her birth certificate issued over 50 years ago her race is described at white, but that wouldn’t be the case now.
Which is interesting because it suggests that a lot of this confusion is new, even in the US.
I think a lot of it is to do with identity politics/critical theory/cultural marxism (though I hate the latter term.)
Lots of these terms - white, POC, Latinio, Hispanic, even BIPOC - maybe all of them, do not mean "oppressed group." They mean something else, like people from a Latin culture, Spanish speaking people, people from no-European backgrounds, whatever. It may be that these groups are opressed, or maybe they aren't, or some members are. That can also change over time and in different places.
This idea that people who belong to a specific group are always grouped together because they are oppressed is a shallow understanding in a lot of ways. For that matter the increasing use of the word "white" to mean oppressor class is also not only inaccurate but makes real analysis of social oppression more difficult, and it lends itself to a deeply racist way of looking at the world.