I don't come across Kreel a lot. Today might have been the first time I've seen in him the Tower for months, hanging out with some other clowns that had escaped from the circus. So the strange behaviour going on with Zomm's Putrid Claw (basic attack) if he has the Splashback debuff is new to me. I'm guessing it's because of Zomm's epic. Check out the picture below:
As you can see from the targetting arrow, Zomm can only attack the Ekko on my team. That's not helpful. It's not a glitch with the arrow, as attempting to attack either Kreel or Deadeye gives me the "invalid target" message. If I didn't have any special abilities powered, I would have had to attack my own team.
Zomm's other abilities look like they work as intended while Splashback is active. For example, I was allowed to attack the enemies with Taste For Brains.