An automatically generated ambient probe that captures environment lighting.
The SkyManager automatically generates this ambient probe to ensure that environment lighting affects your scene and the GameObjects in it by default.
Unity does not use this probe to affect GameObjects that you manually associate with Light Probes and light maps in the Global Illumination system. This is because manually generated Light Probes and light maps include an environment contribution by default.
As a result, adjusting this automatically generated ambient probe does not affect Enlighten Realtime Global Illumination and Baked Global Illumination lighting results. If you want to affect Global Illumination values with this ambient probe, select an AmbientMode and make any manual adjustments needed to use that mode.
To disable the environment contribution in the lighting result for a scene or GameObject that does not have manually created light maps and Light Probes, disable the default Reflection Probe and the ambient probe. For more information, see Disabling the SkyManager.
Additional resources: ambientMode, SphericalHarmonicsL2, The Lighting window.