I think that special rules for Playoff games might be considered here, but in general thsi could be fixed.
All turnovers are already automatically reiewed. Give the replay official the ability to call a PI or other penalty in cases like the Decker pick 6. Overturn the pick and give the offense the ball back with a first down.
There was clear PI there, but not called on the field. The Bang -bang play excuse given during the game then would not come into play. Decker was hit with the ball in the air and clearly before the ball arrived. The PI definitely resulted in the turnover, and it should have been overturned.
This also would have allowed the Replay official to oveturn the result in the Seattle Green Bay game early in the year. Tate would have been called for offensive PI on the hail mary for throwing a defender out of the way, to get position for the reception.
As far as PI in general, I agree that the penalty should be a max 15-25 yard penalty. Spot foul up to 25 yards. If a player is doing it on purpose repeatedly, then tack 15 on for a personal foul also.
But if you are going to stick with a spot foul ( and the possibility of a 50-60 yard penalty) then the replay official should be able to drop a flag on either teams principals in the play. All scoring or over 15 yard PIs should be reviewed.