This does exist but not in the way this dork is talking about. A "performative y'all" is how I would describe the type of y'all that people who did not grow up saying y'all use. One way I can catch it is if the y'all has extra emphasis on the last l. It fades after repeated usage and comfort.
Minor point but I really hate this performative “y’all” people do to try and appear more folksy. I don’t type in a Yorkshire accent and I did people would rightly tell me to shut up.