Of course there were lockdown puppies. The majority of people who purchased puppies took notice of the supposed "rules" about what they could and could not do, when if fact as the OP states, you could go out as many times per day as you wanted. This did not happen though, pups were not socialised fully due to them not meeting and greeting other dogs and people.
There were no training classes. Dogs could not go to the vets, or their owners were not allowed in with them - this is all stressful for a new puppy.
When dogs did go out, all they saw was the majority of the population with a mask on, dogs read facial expressions.
Lockdown was an unmitigated disaster for new puppies - many people should not have got them.
There may be an increase in problems occurring, probably because there has been a vast increase in dog ownership due to lockdown. In addition, it encouraged excessive breeding from many backyard breeders who saw lockdown as a way of making a lot of money, with no thought to health or temperaments of the sire/dam.
I met a lady walking when out with my dogs, I will not say what breed she had but she openly told me her and a friend had decided to have a litter of puppies each as they could make in excess of £20k - no health testing, the bitches were both under 2 years old, no experience of breeding. When I mentioned it may not be a good idea her answer "everyone is doing it".