Guess Jean jacket marked as medium, but fits like a small

Used but in excellent condition. No visible wear. A beautiful dark blue denim. This jacket is labeled as a medium, but it fits more like a small. I am a small and it fits me perfectly. Bought it for my step daughter and she loved it, but of course teenager’s their taste changes every day…and she decided she doesn’t want it anymore. Smoke and cat free home, but dog friendly home.