That happens when you are not using a shader and plug a texture directly to the surface of the material.

Shaders define what happens to light rays on the surface of an object. Without a shader... well... there is no shading...

That happens when you are not using a shader and plug a texture directly to the surface of the material.

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Plugging a texture directly to the material output, the texture becomes emission source.

Shaders define what happens to light rays on the surface of an object. Without a shader... well... there is no shading..

Use a shader and plug the texture as color.