Probably since about early 1990s. Maybe I should say civic nationalism instead of multiculturalism but I think most liberals would reject the idea that ethnicity or heritage were important in determining nationality.

this is categorically different from multiculturalism. all cultures are not equal, and some are antithetical to liberal values. a diversity of people is good, but as much as possible society should prefer a common banner and shared loyalty, or view of civic duty. America has for a long time shown that there can be a combination of national identity and ethnic and religious diversity.

to that end, i think arguments for or against different degrees of immigration are valid and worth engaging (as opposed to shunning under false labels).