The issue isn't the front of the pump, I have mine set at 25%-50% low variance and my clowns get blown across the tank also and it is fun to watch.
The problem lies in the back and the size of the openings there where a small fish can get sucked in! My blenny loved to swim along the glass and I have no doubt that is what happened.
I understand the front of the Powerhead is not the issue. I get how Power heads work!
What I am saying is that My fish swim by it all the time front back sides I personally Never had the same issue you had by the looks of the photo. My clowns look to be smaller roughly a inch and a half. But that is neither here nor there. I just wonder with the flow in the tank did it get blown around then sucked up? My Bubble tip did and that's how it disappeared in less than 24 hrs I was ticked at myself for that one. I do not know if you said you watched it get sucked up or noticed it missing from the tank.
It sucks to lose anything in this hobby as it cost good money!