This stuff has been floating around for a while, it's not exactly new. I remember my mom telling me back in the 90s that at some point we'd be a majority-minority country, which she framed as a positive thing.
White racists in the south have been trying to start a race war for more than a century.
1. Wattenberg 1987 (ISBN-13: 978-0345343994)
You must be an exception then, because even NBC has joined in on the fear-mongering:
Soon, more than one-third of Americans will live in states where ethnic groups outnumber whites. Such demographic shifts are fueling criticism that the word ‘minority’ is increasingly inaccurate, obsolete or even offensive. - https://www.nbcnews.com/id/wbna9001157
This is interesting phrasing, implying that there are two kinds of people -- people with "ethnic groups" and "whites" which apparently don't have ethnicities?
"ethnic: Relating to a population subgroup (within a larger or dominant national or cultural group) with a common national or cultural tradition."
(from an online version of the Oxford dictionary: https://web.archive.org/web/20200108002157/https://www.lexic...)
Also, to your point, the usage section of the entry encourages using more specific terms:
"Ethnic is sometimes used in a euphemistic way to refer to non-white people as a whole, as in a radio station which broadcasts to the ethnic community in Birmingham. Although this usage is quite common, more specific terms such as ‘black’ or ‘Asian’ are preferable."
I've been aware of this for a while, and its not just something 'the left' concocted, nor is it new, and has been a bogeyman of reactionary nutjobs going back decades. I remember hearing it as a post-Jim Crow trope in the 80s, and I thought it was stupid then, and it's stupid now...but stupid and violent paranoia is what gets you things like the recent Buffalo shooting (among other things), which is likely why its getting a lot of news ink now, and justifiably so.
It's not limited to the US either, but we're just really good at giving it a fresh coat of double-speak paint via buffoons like Tucker Carlson and any available Trumpkin du jour.
Here's an article from last year detailing dozens of instances where "a few nutters" endorsed this replacement conspiracy theory on one of the largest cable news shows in America: https://www.mediamatters.org/fox-news/tucker-carlson-fully-e...
And that's just from one week.
When mass murderers are quoting Tucker Carlson I don't think you can, in good faith, place the blame on the liberals.
How about some "fringe nutters" rambling in the NYT? https://www.nytimes.com/2022/05/13/books/review/francis-fuku...
Or https://www.theguardian.com/books/2022/apr/21/the-great-expe...
Or https://www.cfr.org/book/great-experiment
Aaaand so on...
edit: or, an excerpt from German TV, about a minute:
https://www.youtube.com/watch?v=7bqjwvfe4jA from 2018
edit: related https://duckduckgo.com/?q=weapons+of+mass+migration
The Turner Diaries are basically classic literature to the extreme right wing and have been around for well over 40 years now.