The documentation lists its limitations, which include daylight:
> The Camera Shy Hoodie is not an end-all-be-all for hiding your identity. It’s good for one thing, blowing out the view of night vision (IR) cameras in low light environments. It’s not effective in sunlight, most indoor lighting, or against conventional cameras. In fact, you will draw attention to yourself if you wear this in a context in which the security
cameras are actively monitored. In the view of an IR camera, it’ll look as if you’re flashing a light directly at the lens. In addition, the LEDs need to be a minimum distance from the camera to be effective, as the cone of light from them needs to be wide enough to overlap with the cameras view of the wearers head. In practice, this is about 12ft (~3m).
The idea is designed to exploit limitations with the camera's auto-exposure, and I presume a requirement to do that is to strobe a light that outshines the ambient light by n times. That works at night because there's so little ambient light, during the day you'd have to outshine the sun (and the sun is really bright).
