Wait, I just came up with another theory,
Ok, What if:
They're going through the cave and tunnels and all that good crap. Then they finally make it to the shooting star thanks to centipedele (I that's how you spell her name). But, Bentonite is so powerful hungry that she struggles to take control of (Y/n). She does and shes trys to take it, only for the star to melts (Y/n) hand off. Bentonite is so shocked that she loses focus and (Y/n) takes control again and freaks out about her hand. Pearl covers Stevens eyes and Garnet grabs (Y/n) so they all and go back to the temple. They make it back to the temple and freak out even more about (Y/n)s hand. But to everyone horror, (Y/n) asks Pearl to cut off the rest of her hand.
that's just how I imagine it ♀️