But my old dog never did this.

My old dog was never that active! My old dog learnt this much quicker.
I feel for the puppies that have to follow an old dog.
I think we tend to forget and we are often more than 10 years older than when we had the last puppy.
Puppies have not changed much, they nip, they chase, they wee in the house, they don’t sleep at night, they want to be with you all the time.
When they are teenagers, they will not come when called, they seem to have forgotten basic cues, they regress in house training, they become a bit stroppy at the dog park.
And then they turn into well adjusted adult dogs!
No, the puppies do not change, it is us who forget!sleeping