Light Stain on back of skirt. Looks like it should wash out. Please see pics. Thank you

The Aerie Black Bubble Skirt with Built In Shorts in XXS is a stylish and comfortable garment perfect for casual occasions during the spring and summer seasons. Made of cotton material with a pull-on closure, this skirt features a ruffle accent and a bubble hem design. The skirt is machine washable and crafted by the Aerie brand, making it a versatile and trendy addition to any woman's wardrobe.