I have for about two months BN 1713 Soft Calf (I posted about the bag here
My first Prada and I'm like a crazy! ).
Lining is cut from soft leather. Unfortunately after two months of wearing there are two black horizontal lines

It apparently arises when worn. I don't know from what it might be. My camera could not capture it very well, so I marked the location with arrows. Dirty (dark grey/black) lines lead among those arrows on both sides. I tried cleaning it with spray for cleaning skin, but it is still visible and I am afraid that the more I'll try to clean it, the more it will look dirty and not good