I'll have to examine the original RAW or JPEG file....! Seriously, though it's so much more in relief than other shadows, and it goes from the chin to the shirt without a break or change in opacity.
AI is better than no I at all!!
OK, thanks, Dan, mystery solved. The blackness of the interior of the shirt collar solves the puzzle.
I loved Humans, the TV series, and anything to do with AI. Any other recommendations for movies or TV series?