Insane is just that. Insane. With all the bonuses the AI gets investing in quantum upgrades it probably could make a punisher deal 4k damage.

Lag would more likely be the cause. You can always try watching the replay. 

Because in your teammate's case, you're likely seeing things just slightly delayed. But in your own case, you're experiencing the actual effects of the lag. As in, that Punisher already killed your launcher, but you didn't notice it until all the damage happened (Which appeared to be one really strong shot).

Well, i played a lot more games, and ill have to say, this instant kill is a BUG! Tried with a lot of difficulty scale, even with a friend helped me deducing, so the problem is, when ANY AA structure is being upgraded, even the lightest attack oneshoots them.. This isnt normal in my opinion.