When the game stops, Roving Umpire notices and often comes close to dealing with it, so there are not many scenes to worry about rules other than counting scores usually. If you have not read the rule book, there is a rule that you are likely to breach inadvertently, you should not leave the court without permission during the game.
This is a principle in all cases, whether it is nosebleed, going to the toilet, racket's reserve is gone, forgetting a water bottle or towel, or if a tennis ball fly out of the court , If you leave the coat without permission, you will be disqualified strictly.
If you go outside the court, let's take permission from the referee.
I have seen the players who left their coat without permission during the game many times (in particular, many ball picking out of the court), but I have never seen a person who was said to be disqualified . Tennis is often strict rule management, and that is salvation.