No evidence has been provided to prove that there has been a definite change in the early 21st century, and that the supposed new meaning is "non-standard." Maybe I'm missing something, but are you claiming that right-wingers  especially in the United States  in the 20th century and earlier used the term "left-wing" to mean something positive, and only in the past few years starting using it as a pejorative term? Also, saying examples "abound" is uncited opinion, so I changed it to "Examples include the following."