I didn't use it much growing up since they moved west when I was young. but it turns out that "y'all" is surprisingly nifty: a gender neutral, 2nd person pronoun for a group of peope. So I picked it up more in adulthood and put it into my daily vernacular.
It's a term commonly used in some of the "Southern" US states.
And also by Indian Christians (Catholics) in some parts of India, such as Mumbai and nearby areas, like Pune and Goa, along or near the Western coast of India. Partly grew up there, and also did some of my schooling there, that's how I know this.
I don't know if there is any historical connection between the usage of that phrase (y'all) in those two areas (of the US and India).
It could have been, via (US) Christian missionaries coming here. There were and still are some of them, in some parts of India, from more than 100 years ago. Again, I know this from experience.
That general area of India, and some other parts, do have a relatively high percentage of Christians.
