Ah, I see, sorry I misread the op. What version of ACF did you upgrade from? Just curious because I can’t remember when this changed but I have noticed that the “name” attribute of sub fields does act the way you indicate for a while now.
There is another field attribute with the index of "_name" that contains the actual name of the field, this has also been there for a while. Like I said, I don’t recall when this was changed.
