Apparently the new ageist insult beyond "boomer" is "double-spacer" -- people who were taught in school to always follow the period at the end of a sentence with two spaces when composing the next sentence. If you went to elementary school after the internet became widespread, you are not likely to have been taught that. So double-spacing has now also become a shibboleth, albeit indicating the typist's age, distinguishing early millennials and Xers, who are now entering middle/old age, from the younger generations.