How to reproduce:
1. Open the attached "HDRPSpawnLightingDOTS"
2. Open up the SampleScene
3. Observe in the Scene view there are three cubes bright, less bright, and bright (the middle one (less bright) is part of the subscene 'sub')

Expected: the object from the subscene should look like the rest of the cubes in the scene
Actual: the cube from the subcsene is less bright (see the seneview.png attached in the Edit section)

4. Enter play mode
5. Observe that the cube on the left is converted to an entity and is now less bright (like the one from the subcene)

Expected: in play mode entities converted from game objects should look the same as they do before they are converted
Actual: converted entities look less bright (see the gameview.png attached in the Edit section)

Reproducible with: 2019.3.16f1, 2019.4.3f1, 2020.1.0b15, 2020.2.0a16

Note:
-Different behavior on macOS, cubes brightness looks like in gameview.png
-Could not test with earlier versions because of the thrown errors