My breeder research has told me that reputable breeders usually have waiting lists and don’t advertise except for the akc website (advertising upcoming litters or litters with their paws on the ground). I’ve always been surprised when I read of someone saying they’re buying such & such purebred puppy in a couple months but haven’t contacted breeders. That tells me they have no idea how to find a reputable breeder though some of us have gotten lucky.
I’m sorry you had to return the puppy but I think it was the right move.
