gray part of the sky in the new technical visualization deferred

So I wanted to go back to the subject of this bug because this bug is a probable bug that is happening with all PBR textures where the sky has a black part 

 

1 how to see it happening 

2 To see it happen is to look at the opposite side to the sun or the moon in all the textures and then you will see a black spot in the sky which in my opinion looks ugly in the sky but that's my opinion