@Talia1108
It kind of looks like Airbnb applied their 20% “new listing discount.”
Or possibly it has something to do with “smart pricing.”
I just checked your listing and it said I could have 4 nights for $400.
If you don’t want to accept the guest at that price you could contact them and ask them to pay the appropriate price or cancel.
I doubt that CS would be helpful but you could try. . . and try… and try again to make sure it doesn’t happen again.