Forever 21 Plus Black Bow Bikini Top

This is for women who are between sizes XL-1X so they call it 0X. I have worn this top a couple times but it doesn’t fit me anymore, it has a couple small white lines on the inside that cannot be seen from the outside, on the back of the bikini it has a white smudge I haven’t washed this so I’m unsure if they can come out.