Is that the normal disciplinary procedure for that?
If you are gone for more than 2 minutes by the time you return you are automatically penalized and given the loss regardless of the actual match outcome. This may seem unfair but unfortunately it’s a rule that’s in place to ensure that players try to return as quickly as possible and to prevent those who would otherwise abuse is the leaver system by attempting to sneak back into the game when they think it’s about to end and avoid the suspension. Details here: