Rectangle in sky about an hour before sunset

Driving east to west on Taylor St I saw a rectangle object.in the sky. At first, I thought it was an advertising banner being pulled by a plane, but there was no plane in either direction, and the object seemed to be standing still. I kept my eye on the object for about 1 minute before it started to dissipate. I quickly pulled into an empty lot to get out and take a picture, but the object was gone. I was reading about the new Bluewalker 3 satellite, but this object wasn't that high in the sky.