Steps to reproduce:

1. Import the attached project
2. Open one after the other "Lightmapsky.unity", "Lightmapsky2.unity" and "Lightmapsky2_Enl.unity"
3. Optionally: Try rebaking the lightmaps in the scenes.

Notes:

- The exposure is tweaked in the scene so that the background sky is exposed the same between all scenes.
- When using Gamma color space, the rendering is way closer, although not identical.
- This is particularly affecting HDRP as working only in Linear color space and physical light units (high exposure for the sky) affects the ambient baked lighting.
- Scene "Lightmapsky2_Enl.unity" is using Enlighten as static lightmapper and doesn't seems to be affected by the issue.
- Affects both CPU and GPU lightmappers.