Unfortunately all disconnections and game crashes counts as leaving the match and will be penalized appropriately. The game server has no way to discern a legitimate disconnection or game crash from one that is forcefully caused by a dishonest player to bypass leaver penalties. You can learn about this policy here:
If you are completely season banned (the Competitive Play option is locked with no timer displayed), then that means you have at least six or more games in this season where you left a match. Season bans results in your Competitive Season Results being disqualified and you lose all end-of-season rewards including Bonus Competitive Points. If you get three or more season bans, you will be PERMANENTLY banned from Competitive Play. Competitive Season and Permanent Bans CANNOT BE APPEALED.