Hah! Obviously this girl has never had a puppy before. They bite. They bite anything and everything. They will chew anything and everything. Chair legs, your legs, door/window frames, and carpets can be endless fun for them (they'll leave a looooong visible trail where they pulled up until they ran out or got caught 🤣).
Her reaction was great though! If a puppy bites you it won't really hurt that much (more of a gentle pinch than an "Ouch! Fuck!") but you have to sell it! When a puppy bites you, react loudly like they just sucker punched you hard in the face while insulting your mother. Act! And don't interact with them for a minute or two. If you're holding them, put them down and be like, "I don't play with dogs that do that! 😤"
That's how they learn that biting is bad. Also, always have treats handy for when they do good things and teach them to have a gentle mouth the same way as teaching them not to bite. Keep a death grip on the treats when you're teaching them this because if they were too rough but got away with the treat they won't learn.
BTW: Puppies have sharp teeth. Way sharper than an adult dog. You're much more likely to get scratches from their biting than bruises.