Maybe that's a cultural thing in your country but here we have Indian and Chinese expat, either working for large multinational companies or international organization. Nobody here is going to call an Asian or African working for WHO, or UN agencies on temporary basis an immigrant. Immigrant are people looking for permanent residency, and we btw do have a lot of British and American immigrants.
that might be an american thing? as a brown person when i was living in the UAE i was definitely an expat, since i had no intention of settling there (or indeed any particularly good option to).
White people living in retirement communities in Thailand call themselves and are called expats.
https://www.theguardian.com/global-development-professionals...
https://www.theguardian.com/commentisfree/2019/apr/10/immigr...