On November 8th, 2019 Eddie Pepperell disqualified himself by hitting all of his inventory of balls in a lake.
During the Mayokoba championship in Mexico on November 15th, 2019, Russell Henly got a penalty of 8 strokes because of the breach of the one-ball rule.
The PGA Tour local rule
A player must keep the same type of ball for the entire round. The player is not even allowed to change the color of the ball. The penalty is 2 strokes for each hole played in breach of that local rule.
Why Pepperell was disqualified?
When he emptied his bag, he could have asked another player for balls. As long as they are exactly the same make. But he decided to quit.
Why did Henly make this mistake
Titleist gave a few balls to players with a different spin rate. There is a small dash (-) near the inscription. By mistake he took one of those balls for 4 holes.