A broken tail would have been really obvious to the breeder from a really young age. With the fact that you have got a damaged pup ( not mentioned by the breeder) and one that was not microchipped and you are saying the breeder has "many" litters, you appear to have bought from a puppy mill, or at the very least a breeder with no scrupples. If this assumption is wrong then I apologise to you and the breeder, but if not then shame on you.
Unless you intend showing the dog or doing something along the ratting sport lines, I would not worry. By now the tail would have set in it's current position and it would be a traumatic op to fix it.
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