Are you thinking of Jeffrey Maier, the kid who caught a ball in Yankee Stadium, during the playoffs between Baltimore and the Yankees in 1996?
As I recall, the outfielder couldn’t catch the ball because Jeffrey reached out and caught it from the outfield seats, and in spite of Baltimore protests of fan interference, it was ruled a home run for Derek Jeter.
I looked it up. It was Steve Bartman in 2003, Cubs playoff game.