Depending on whether it is being observed or not, light behaves differently
Light appears to travel as a wave when it is not observed, creating an interference pattern that is in line with wave mechanics. The same light, however, behaves like discrete particles when an observation or measurement is made, collapsing the wave function and removing the interference pattern
This dual behaviour implies that the way light is currently implemented modifies its basic characteristics based on observation, which could point to a design flaw or an unreported feature