If your game is 4v3 , the enemy team is 3 people, and then the enemy team has 1 person disconnect, this run will be passed or will be rejected

Provided you are talking about 4v4, it will be rejected. Disconnects are considered players who do not make up the maximum capacity for a game. Given the rule for 4v4 is that no more than one of the opponents can leave, even if they left before the game (or never filled in the first place), it is counted, meaning any additional disconnects would invalidate the run