When you set a Scene’s Lighting Mode to Baked Indirect, Mixed Lights behave like Realtime Lights, with the additional benefit of baking indirect lighting into lightmaps. GameObjects lit by Mixed Lights cast real-time shadows up to the Shadow Distance you define in the Project.
When you set a Scene’s Lighting Mode to Baked Indirect, Mixed Lights behave as follows:
Because all shadows from Mixed Lights are real-time in Baked Indirect Lighting Mode, this can impact performance. You can reduce this impact by using the Shadow Distance property to limit the distance up to which Unity draws real-time shadows.
In the Baked Indirect Lighting Mode, you can subtly change the properties of a Mixed Light at runtime. Changes affect the real-time direct lighting that the Mixed Light contributes to the Scene, without affecting the baked indirect lighting that the Mixed Light contributes to the Scene. This allows you to combine the benefits of baked indirect lighting with some of the dynamic capabilities of a Realtime Light. This works especially well in Baked Indirect Lighting Mode, due to the lack of precomputed shadows.
You must be careful with runtime changes to Light properties, and only make small changes that don’t cause unrealistic combinations of real-time direct and baked indirect lighting. For example, if you bake a red Mixed Light into a lightmap and then change its color to green at runtime, the direct lighting is green but the indirect lighting baked into the lightmap remains red. The same applies to moving a Mixed Light at runtime: direct lighting follows the Light’s new position, but indirect lighting remains at the position at which the Light was baked.
This video shows an example of how to slightly modify a Mixed Light without causing noticeable inconsistencies in the indirect lighting: https://youtu.be/XN6ya31gm1I