Most digital cameras see farther on the low end than humans do and it can do some odd things. It made the news with the Sony? camera that had a mode specifically to use this--turns out it sort-of sees through many swimsuits. Or a video I've seen of firefighters caught in a burnover--the fire looked very weird!

Genuinely don’t know. The hack here is exploiting artifacts from over exposure for the camera sensor. As to if they have mitigating features to filter non visible light, I’m actually curious.

I doubt it, that is a lot of extra cost against an attack that doesn't exist today.