He was tripped up by Ragnow’s very noticeable grasp. The ball was already in route to the end zone when he arrived.
Detroit would have had to repeat the down from the 11-yard line rather than scoring a score if the holding penalty had been correctly called. A terrible missed call resulted in the Packers losing.
The officials were the only ones who did not see the punishment in real time. They failed to raise a flag. Instead, since the play was not called back, the Lions gained a three-point lead.
If that wasn’t terrible enough, the NFL attempted to hide its error by starting the play immediately after Nixon had gotten out of Ragnow’s hold and posting the highlight of Detroit’s score to X.
It was a deliberate edit, given the league’s prior postings. Just before to the snap, the great majority of the highlights posted on the NFL’s official X account start. Not with a penalty for a missing hold!