You have added a new skybox to your scene. However, the Main Camera is only rendering a solid blue color. What is the issue that's occurring?

The issue is that the background type of the Main Camera is set to Solid Color. In Unity, when you add a new skybox to the scene, the camera is typically expected to render that skybox instead of a solid background color. If the camera’s background type is set to Solid Color, it will override the skybox setting and display the specified solid color instead, which in this case is blue.

For a camera to properly render the skybox, you must ensure that the Camera's Clear Flags property is set to 'Skybox.' This allows the camera to render the skybox that you have added to the scene, enabling it to appear as the background instead of a solid color. If this property is not set correctly, you may only see the solid color background, even when the skybox is correctly applied to the scene.