I have kind of the same problem, but - yet still a little worse:
My iPhone 8 has been dropped on a parking lot with an uneven surface - and run over by a car!
So, the entire back housing is bend quite a lot (strangely enough, neither the back glass or the screen seems to be damaged at all).
But it looks odd, and being the skilled industrial technician I am, I’ve tried to bend it back into the correct shape. This cannot be done, since the aluminium kinda hardens the first time it is bend out of shape - and cannot be forced back to its original shape.
So, it would be very appreciated if anyone could help, regarding where I can buy a new back housing.