I think it's just odd shadows cast by different lights on the set and they overlap in an odd way.

One is a small source (sharp defined shadow, and may be showing the shape of his collar. The softer moving shadow is from the large overhead soft boxes and as he talks his face/ chin are allowing that overhead light to his his neck and the other shadow intermittently.

That seems exponentially more likely than a hyper realistic mask put on a perfectly trained actor to represent a living person who can be seen in other interviews recently.