Okay,  let me explain this.

“Y’all” is a correct amalgamation of “you” and “all,” which is presumably what we mean when we say “y’all” most times.

“Ya’ll” would have to be an amalgamation of “you” and “will” — like “you’ll” or “he’ll” or “we’ll”.  I can see that there would be cases in which this would be a correct spelling, but 99.9% of the time this isn’t what you mean, people.

I know not all y’all will agree about this.  To which I say:  my blog.  Take it elsewhere.  This is one error on which I will not budge.