Cleverly designed bath-use glasses that don’t fog up make a splash in Japan

Not the person you asked, but I'm guessing it's because it feels oddly empty and strange (notice how the back wall is a mirror that feels like a wrong and overly dark window, and the seats are odd). Essentially its a liminal space, which many people find unsettling.

Edited to add: plus the steam in the room causes the light to seem strange and overly diffuse