For anyone who takes their Overwatch seriously, the thought of bug that renders the player with an instaban is about as terrifying as it gets.
The problem seems to stem from quitting a competitive at an unspecified point in the loading process. As explained by Chromega:
“Basically, it seems to happen if someone leaves right as the competitive match is loading or something. The match goes into a 'waiting for players' state, odd for competitive. The match tries to start, fails, and returns to 'waiting for players' with the same players and repeats. Folks who have seen this bug lose HUNDREDS of SR, and, most importantly, get season banned immediately, even with no prior disconnects. Seems like it affects everyone in the match, but I can't confirm.
“I've found claims of several people who have hit this bug. Consider this a PSA, you may one day queue for a match that instantly bans you, and Blizzard will not help.”
As far-fetched as the claims sound, they were backed up first by other users, and then by Blizzard itself.
“We recently identified a bug that, in extremely rare cases, can cause players to lose their skill rating progress and receive a seasonal ban from Competitive Play without any prior penalties for leaving early or being kicked for inactivity,” Overwatch director Jeff Kaplan said.
“This bug is a high priority for our team, and we’re working on a fix to prevent further instances of it occurring as we speak.
“In the meantime, we’ll be removing the seasonal ban for all players affected by this bug as well as restoring their skill rating. To date, this bug has impacted fewer than 200 accounts, but we’ll continue to monitor for additional occurrences and provide assistance until we can implement a permanent fix. We don’t have an ETA to share right now for when the fix will go live, but we’ll update this thread as soon more information becomes available.”