“Yinzer” is a local colloquial term used to describe a native Pittsburgher. The same way people from the U.P of Michigan call themselves Yoopers.
The origin is the second-person plural pronoun “yinz”, which is Western PA’s answer to “y’all”.
Example: “Are you all going to the South Side?” in the local dialect is “Yinz goin’ dahn Sahhs Side n’at?”
Interesting.