The “observation” that occurs during that particular aspect of the double slit experiment refers to photons that are gathered by a sensor. But the OTHER photons that “miss” the sensor are the ones that behave differently in a situation of observation wherein their fellow photons are captured.
The process of observation itself has no known physical interaction with the particles being studied. THAT is the wonder of the experiment.
And photons don’t hit or deflect other photons like little balls.
Meno: Zero meant that ambient photos from light sources in the room bounce off the photons and enter the eye or camera. He didn’t mean the eye emits photons. (although the eye does actually emit an insignificant amount of photons). Of course the observation referred to here is neither by eye nor camera.