Seems to be a issue with transition of DOF and focused objects, where translucency, at least what appears to be the issue, seems to go hay-wire.
PS don't be hard on those Norway Spruce, they haven't received their PBR materials converts yet. :P
I don't see what you mean. On the left I see a little bit of blue sky poking through, on the right, nothing strange.
Look at the foliage shadows. It's all lit up through the DOF transition zone. No dark shadowing. You can see where it goes from an excessive translucency effect to a more subtle what was defined in settings look having deeper shadows within the foliage.
Maybe there's something out of focus right in front of the camera, and the "light" you see is the out-of-focus object.
I'll lift the camera out of the grass to see, could be. But the effect lines up with where I set the DOF focal distance at in the preview.
Actually, I do need to raise the camera, you are right. Looking at the pre-pass, I can clearly see the green pixels of a single blade of grass stretching to the top of the frame. You da man.