I was looking for something to this regard. In die RSA vs England 2023 RWC match the scrumhalf catches the ball and ran back to his goal line and kicked the ball over the dead ball line. Time was up for the first half. Although the time was up the ball was still in play. If he kicked the ball over the sideline no issue en of half, but running back to the goal line and deliberately kicking the ball over the dead ball line should have been a 5-meter scrum for SA.
After kicking the ball over the dead ball line, the ball was not in play.
I often wonder in situations like this, and regarding the touchline, why don't players simply walk over the line while carrying the ball, why do they walk up to the line and then kick it?
Incidentally, I remember a game in my final season that seemed to go on forever despite several scrums (knock-on, forward pass, collapsed maul, whatever) and a couple of lineout from players tackled into touch... when I later queried the ref he told me the ball had to be kicked into touch to make it dead... I think we played a 50 minute half