Lighting Dramaticly changed after restart

Hey everyone, i had an issue today. yesterday i was working on my scene and i had finished lighting it how i wanted it to apart from small touches before finishing up.
however today when i started up my scene this is what i got to see.

And this is how it looked before i went to sleep, i saved everything when i closed. and i can’t find anything that should be causing such a dramatic change.

I’m thinking this is something around the ‘moveable / static skylight / light build’ area.

Have you changed from a static to stationary / moveable skylight? Have you rebuilt light?..