In Junkenstein's Revenge, there is a Zombardier enemy which attacks players with blue energy projectiles. It sometimes feels like the Zombardiers collectively choose a single player to shoot at for the entire game.

I've had rounds where the Zobardiers ignore me when I'm standing next to them, while other times they've gone out of their way to shoot me from across the map.

What determines which player the Zombardiers target in Junkenstein's Revenge?