A puppy challenging its Mother.
Many parents wake up one day to their child no longer listening to them or talking back. Puppies are no different. These kids and puppies are dominant. In the dog world, a Dog Mother does not tolerate this behaviour and continues to correct her puppy until the puppy understands it has to listen to its Mother. Many people are intimidated by dominant puppies, even puppies this young, because those teeth are sharp and hurt.
It is the confidence a Dog Mother has when correcting her dominant puppies that let's them know she has what it takes to protect them from danger. Your dominant puppy is watching you all the time to see if you have what it takes to protect them and if you back away from your puppy when it challenges you, it knows you can not protect them from danger and they will no longer listen to you, no matter how many treats you may have.
If you have a dominant puppy, even just 3 months old, who intentionally nips and bites, this behaviour will get worse as the puppy gets older. The ONLY way to correct this behaviour is to learn how to correct your dominant puppy the way its Mother did, they way this Dog Mother did. She is not forcing her puppy on the ground and pinning it, she is asking or telling her puppy to lay on its side and relax. You 'never' pin a dog or a puppy, they should willingly lay down and relax on their own. You just touch their neck to ask or tell them to do so until they do so. Then lots of gentle affection when they relax to thank them and to feed in the calm and relaxed energy you want your puppy to be.
When treats don't work, being their Dog Mother does.
Cheers ✌️