This last season, In response to the Detroit Lions losing a game in Houston because the Lions’ coach through a challenge flag on a long run. The refs actually would have called the play back, but since the coach through the flag, they couldn’t. The play stood and the game was over.
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.