The question is: why would you add this description if it's completely unrelated?
By specifying this attribute, the commenter wanted to draw attention to that fact, that this was a lesbian. So, why exactly would that fact need attention? Best case it's completely irrelevant, more likely it's supposed to be some sort of weird bragging or simply an underhanded insult.
Sometimes natural lights comes in at "uncomfortable" angles or simply leaves some corners relatively dark.
So the artificial light acts as a counter light to reduce shadows and create a more even lighting.