the field” is that is under review.

In this case, “the ruling on the field of a touchdown is under further review.”

Otherwise they would have said, “the ruling on the field that the player stepped out of bounds before crossing the goal line, is under further review.”

They always phrase it in terms of what will be the call unless overturned by incontrovertible evidence. “Ruling on the field.” And it’s super important because if a play is going to “stand” instead of being “overturned” or “confirmed” it’s going to have to be what they officially declared to be the “ruling on the field” at the time of calling for the review.

It may not be what was called initially, it’s what they settled on after conversing.