So what I heard a long time ago is that all LED lights essentially strobe on and off constantly, faster than the human eye can detect, though i’m willing to bet the better ones are constructed in a way that you wouldn’t notice at all (whether with the naked eye, or through a high shutter speed camera, as you mentioned), but the shittier ones strobe more frequently and not at a rate that’s as smooth/consistent as the better ones. As a little anecdote, I bought a lower quality light-tablet for tracing a while back, and was getting crazy headaches after using it for maybe an hour or so. Had to stop using it, and I think it must be an example of what poor quality LEDs are like.