One only needs 1 or two LEDs near their face, but they need to be blinking in short irregular intervals. Cameras have mechanical controls for controlling focus and the amount of light they capture, and that can be attacked with these irregular blinky LEDs that cause the camera to try to adjust to the bright illumination from the LED, but then it is gone before the adjustment is complete, but then it is on again, then off again. The result is a person that never is more than a grey silhouette.

I worked in enterprise FR, on one of the globally leading systems, as the lead developer. That scenario defeats pretty much all FR when from a single camera. It can be mitigated with multiple camera views, which few FR systems are setup for multiple quality views at every key location.