Fate and Irony were toying with Shakespeare...As well as a poetic metamorphosis into The Dark Lady Penelope Rich also underwent a physical metamorphosis into a black woman when she performed as an African woman in Ben Jonson's Masque of Blackness. (1605). In this performance Penelope was painted black, wore a black wig and had naturally black eyes - to all observers she would have appeared to be a completely black figure. Ben Jonson was a personal friend of Shakespeare and Masque of Blackness is a performance that Shakespeare would likely have seen.
The sonnets were not published until 1609 but I strongly suspect that they were written 1592-1594 , however this does not preclude the possibility that Shakespeare may have revised them a number of times prior to publication.
It is noticed that Masque of Blackness predates The publication of The sonnets therefore it is not impossible that it may have had some influence on Shakespeare very specifically in sonnet 140 where the Dark Lady ( Penelope Rich) is described as an entirely black woman.