Westernised Asian, mostly used to describe mixed people (East Asian and European), but I have also heard it being used to describe Asians (mixed or otherwise) who grew up in a western culture (at least it's common in Hong Kong).

It's sometimes used for people who are proud of their heritage / background, but it is unfortunately also often used in a negative sense by bad people.

I am not too big of a fan of the term, it's a bit silly and too generalised. Somebody who is part Chinese, Vietnamese, Korean, etc. will all have different cultures, experiences, and traditions! It also doesn't help that it's another term that generalises "Asians" as specifically meaning just East Asian people. However, some people are perfectly fine with the term, and that's ok too!