Like this
That really shouldn't happen. It looks to me like the inside of her mouth has inverted somehow. I'm not really sure what would cause that, to be honest.
Is this a character you loaded from a save? Does it go away when you relaunch the game?
It's random generated, and I haven't tried reloading yet, will try when I can
If you get some time, message me through my support email or in the Discord. I'm trying to hunt down this bug.