Hey there, the technical support forum is still part of the overall message boards and sometimes things slip through the cracks (note the time of your original post was extremely early in the morning for the U.S.). Depending on the moment when you leave a Competitive Match, the match will cancel for the benefit of the 11 remaining players. This happens at the early part of the game. If you disconnect later, an opportunity to rejoin may be possible but you have to return within 2 minutes to not be penalized. As always, penalties will always apply to all disconnections and crashes.
Furthermore, the technical support forum is intended for fixing technical issues and not as a place to appeal penalties (which you cannot reverse any competitive leaver penalty). If you are disconnecting frequently, be sure to avoid Competitive Play and work on common troubleshooting steps. If you need advice executing these steps or want help pinpointing the cause of your disconnections we can help with that.