Why are the surrounding areas except the centre of the image blurry and the focus is also not exact?

When taking images using the Galaxy S20 Ultra, the surrounding areas except the centre of the image are blurry and the focus is also not exact.

A : 

The 108M high-pixel image sensor mounted on the Galaxy S20 Ultra wide-angle lens has a larger size compared to camera image sensors of previous devices. The larger the image sensor, and the closer the subject is, the resolution of the surrounding area compared to the center of the image may seem to be out of focus. 

However, this is a normal phenomenon according to camera’s optical characteristics, and not a device defect. All Samsung smartphones undergo rigorous internal inspection tests, and are always being controlled under Samsung’s high level of quality standards.

It is recommended that you do not position subjects too close to the device in order to take clear photos and keep the proper distances between device and object. (This distances differ by device and camera lens. See the values of below table)