There was a quirk in the replay review rules that said if a coach threw a challenge flag on a play that he was not allowed to call for a review (specifically: turnovers and scoring plays), then the officials would penalize the coach (or the coach would burn a timeout) and they would be prohibited from performing the normally-mandatory review.
I think they’re keeping the penalty, but changing the rule so that the mandated review still occurs. I’d call it a technical correction, not a significant change.
Cost the Lions a game.