Is that her in your avatar?
I have one shyer, a singleton, but not fearful of everything. He did require alot more socialization and sensitization to certain things. Many new things for this pup if he was unsure or scared of, the third time (of exposure) was the charm.
Other posters mentioned the “hand shy” of not wanting to be pet from overhead. That is not uncommon actually. In the wild something coming from above over a small animal was never good. Pet the chest and sides and move upward to rub the ears works best for him.
Boiled chicken makes a nice, mild special treat.
Be prepared for some regression phases, especially 5-12 (or 18) months.
Sounds like you picked a gentle, softer temperament. I bet she will be great for obedience with you and not pushy, dominant.
luckily for you, she is in the critical period for socialization. 8-10 weeks is also a fear period and imprinting can happen. Luckily you got her earlier rather than later because the window on socializing has not closed and you can make up for some of the lack of
exposure . It runs from 4-12 weeks I believe.
https://www.paws.org/resources/developmental-stages-of-puppy-behavior/
Even as a veteran dog owner, I end up googling puppy stages to remind myself every time we hit a new stage!
I kinda side eye the breeders response to you but I don’t know context and tone. I have never had a pup react like this to strangers. Even my shyer one but two of mine were bolder and goofier temperaments over all. They had other things to work on instead. Just remember you are catching up a bit but you are not at all “too late” if this is a covid socialization issue. She may never blossom into lab like and that is ok. But she should improve. As long as you can stay calm and upbeat most of the time, she will feel that. They really are more intuitive about feelings than most breeds. Give it a week and please report back.
Did you meet the mom or dad?