I know it's the vogue now, and people are bored at home.
However buying puppies for £3-5k+ a piece is fuelling crime and animal exploitation. A lot of puppies are being bred in terrible conditions, with health impacts for the mothers and puppies. Criminal gangs are breeding puppies, and also stealing puppies and adult dogs, in order to breed from them. There are multiple stories of people being violently mugged for their dogs.
People will say 'but I got my dog from a reputable breeder' however paying a highly overinflated price for a puppy is fuelling the crime and exploitation associated with the industry, by maintaining high prices. In addition, many breeders are not as reputable as they appear to me, as the high financial gains are attracting unscrupulous individuals.
Finally, what will happen to all these impulse purchased puppies once lockdown ends, and people are expected back in the workplace? Likely a lot will end up being abandoned, or left at home alone all day.
Please, if you want to get a dog, adopt, don't shop, and thoroughly research the decision, including the costs involved in ownership. There are many rescues that will rehome to families, and some that have puppies too, but they won't be purebreds or 'designer' crosses!