The exposure value at capture time. When the scene's exposure differs from this value, the probe's contribution is re-exposed to match. This property is used only in URP.
Setting this value is only meaningful for probes whose ReflectionProbe.mode is ReflectionProbeMode.Custom, where it describes the exposure the custom texture was authored at. For baked or realtime probes, Unity writes the scene's exposure value at the probe's position to this property each time the probe's texture is updated, overwriting any value assigned from script.