You can usually tell by the price who is a responsible breeder and who is not. A responsible breeder will charge much more because they've put in the money to have the parents checked for heart, hip, and eye problems before breeding. That alone will save the owner money in future vet bills. Then there are microchips, first round of vaccinations, and a health check on the puppy. I think most responsible breeders do it for the love of the breed and wanting to keep it going by producing healthy puppies. They're lucky if they break even by the time expenses are added up.
Bad breeders usually charge a few hundred quid and may let you see the mother which doesn't mean anything. Absolutely doing it for quick cash because this way leads to easy money. It boomed during lockdown(s) because everyone wanted a puppy.