Yeah, I've talked about that long time ago... nobody gave a flying ****. I even posted feedback in the feedback hub. What happens is that above the background there's a transparent layer. When your theme is set to white, the layer is also white, and it 'bleaches' the background, however the same happens when your theme is black - the layer is black and the picture gets darkened a bit, however you don't notice that.
I did suggest to remove that layer because it only makes things worse, but nothing changed. I can't get the link to my feedback now, though I'll try to post it if I can.