The skull and especially the jaw bones in an 8 week old pup are not fully grown, therefore as the pup ages there may be changes to its bite. An underbite could become a level bite, unlikely to become a scissor bite.
Bites certainly change as the puppy grows in addition to losing their puppy teeth and the adult teeth coming through, especially with the upper and lower canines.
With any incorrect bites the future of the adult teeth may cause issues, such as the canines not slotting into the correct part of the gums due to the upper or lower jaw not being in the correct position.
The breeder, licensed or otherwise, is breeding and selling cross breed dogs, there is no breed standard for any cross breed dogs, therefore what is a correct bite? Puppy contracts, including refunds or returning the dog should be something you are happy with, prior to picking or taking the puppy home, in fact a generic contract should be something the breeder details with you well before the litter is even born.
Many dogs ive happy lives with incorrect bites as long as the adult teeth do not cause any damage to their soft pallets, even then the problems can be minor.
You may be better looking at pedigree golden retrievers or poodles, speak to the breed clubs and the kennel club to find reputable breeders.