The max rectangle area that can be enclosed in a circle is actually a square. This means that ideally a 1:1 aspect-ratio sensor would be able to collect more information than any other aspect ratio sensor.
On my phone, the highest resolution (in terms of pixel count) is obtained for 4:3 aspect ratio. Does it mean that the camera sensor is physically designed with 4:3 ratio? This seems weird since camera lenses are circular, and optical images have circular symmetry, so a 1:1 aspect ratio sensors would provide the most information.
Then why the max pixel count is not for 1:1 ratio? What exactly a 4:3 ratio is optimized for?