I don't think this means anything, but along with the album cover colours getting darker with each successive variant that others have pointed out, one thing that jumped out at me is how the cover photos are more revealing of her with each one as well.
The first one her face is hidden 1989-style, the second one her face is partially obstructed by her arm and hair, the third one she's facing the camera in side profile (also notably no longer in bed).
It's probably just because all the photos are going to be brilliant because Beth Garrabant is incredible and they're just pretty to look at and they wanted to give contrast to each one, but it does kinda feel like she's stepping out of the metaphorical dark with each version.
Like, she's gone from being curled in bed to contemplating getting up to stepping outside but still covered in (his*?) shirt to...
idk I love cover art can you tell (and I love how Taylor tells stories with hers)