Determines whether cookies should be evaluated by the Progressive Lightmapper during Global Illumination calculations.
Support for baked cookies was introduced in version 2020.1. With this setting enabled, cookies assigned to mixed lights will not only affect real-time lighting as before, but also indirect lighting stored in lightmaps and light probes. Cookies assigned to baked lights will also correctly affect lighting stored in lightmaps and light probes.
This setting is enabled by default for new projects, and disabled on upgraded projects. Disabling it allows to preserve legacy behavior.
Note that globally disabling baked cookies will not speed up baking time.
Additional resources: Light.cookie.