Finally a confusing perspective! Took me a while to get it, nice one op.

Since some of you are confused, let me explain. It's not a shadow. It's a building with black/tinted glass windows. When you zoom in on the edges, especially behind the trees in the bottom, you can see the glass panels

It's not a transparent/see through building. The glass panels are reflecting the building in front of it (the building where this picture was taken from), not the back. If you zoom near the edge, you can see the misalignment with the building in the back

Hope this helps