I’ve not seen the American version of “Masked Singer”. My wife and I do watch the Korean version on KBS which I believe is the original of this genre. It is quite popular and some of the singers are excellent. Many, if not not most, are celebrities, actors, entertainment personalities and sometimes athletes. In interviews after their appearances (unmasked) many say wearing the mask while singing gives them a freedom to sing without fear. I have seen nothing on the Korean show to indicate any hint of demonic influence. I’m curious why you think the US ads for this show appear to you to be demonic. Given US TV proclivites, you may well be right.
Just a general sense of how those costumes look and the remarks of the celebrity board.