The first instance came when a challenge was called for on a pitch originally called a ball, but after the challenge, it was overturned to a strike. The second was the opposite where a challenge was called but the original call of a ball was confirmed.
The ABS challenge system is one where an umpire will decide on a ball or strike pitch as usual, but only the batter, catcher, or pitcher can decide to challenge it, unlike manager challenges from the dugout which are separate.
A screen will show the strike zone and where the ball was thrown to determine whether to overturn the umpire's call or confirm it.
The San Diego Padres even tested out this system during one of their batting practices in spring training as well where everyone can see what the correct call should be on the big jumbotron.
The technology was tested during last season in the minor leagues and received great reception from fans and players alike.
According to the league, each review only lasts around 17 seconds long on average, proving to be nothing significant in extending game time - which has been a huge point of improvement for the league over the years.
Unfortunately, the ABS challenge system will not be in place during the 2025 MLB regular season. Use for it in future seasons, however, is definitely a growing possibility.
Each MLB team this spring training will receive two ABS challenges per game and can retain them if the calls are overturned. These are separate from manager challenges.