Schacht / The Platform: End?

Last year a Netflix film came out with the German title Der Schacht. If you've seen it, can you explain the ending to me? I actually found the idea of bringing the dessert back up to be creative. Instead, I found that about the girl very strange and I wonder why that should be a sign.

It was she who had to be brought back. She was the desert

Yes, but why did it have to be brought back and what is the message?