Thing is...the home team supplies the game balls. If they are under inflated, BOTH teams have to pay with under-inflated balls. they DO NOT accept sideline balls from the individual teams...game balls are separate and controlled.
Did Indy, at the start of the game, complain to the officiating that the balls “didn’t feel right”? That is the time to make issue.
My guess is, if (let me repeat: if) the balls were under-inflated, Indy didn’t complain because the balls would be easier to grip and easier to catch.
NFL Rule:
The home club shall have 36 balls for outdoor games and 24 for indoor games available for testing with a pressure gauge by the referee two hours prior to the starting time of the game to meet with League requirements.