I’ve made this top a couple of times before too, here and here. It’s a white embroidered cotton/linen. The fabric is a bit stiff, even after two washings, bit I love the fit so it should soften up after more washing and wearing.
Hopefully it won’t get stained before this happens. I’m not the greatest at keeping whites white. I do have two messy little boys who love to hang on me with dirty little hands.