Also, it's your job to never let anyone else allow your puppy to jump up on them! They will say, "It's OK, she's just a puppy, I don't mind if she jumps on me". You must rush in and pull the puppy down immediately, put your pup in a sit, praise the puppy then scold the person ! Continue to hold the puppy in a sit and let the person greet the pup. Explain to them they can never allow the puppy to jump on them - the puppy must sit to be greeted. To stop the jumping up behavior in pups, I do as much people training as puppy training!
Nobody likes to have a handful of groceries knocked out of their hand or get muddy paw prints on their new pants as they walk through their own front door, let alone someone else's front door. Jumping up can be a cute greeting when you have a small puppy or dog at home, but as time goes on, it can become quite annoying to you and your guests. Teaching your dog to calmly greet you and your guests, without jumping, will create a much more enjoyable environment to enter into after a long day at work or when receiving guests at home.
You shouldn’t stop this type of jumping. You need to diagnose your dog's issue and remedy that. If your dog is just stressed being in a new situation, you should calmly get them off of you, offer them a treat to calm them down, and have them sit politely beside you until their stress level has subsided (or take them somewhere else so that they can calm down if it is taking a while for them to calm down.) But most of all, please do not just ignore this behavior change.
If a dog is stressed or afraid, their demeanor and typical behaviors will change. If you see this in your dog (or really any dog you know) you should step back and check on your dog. Are they hurt? Did a new dog come around they don’t know? Has the weather changed? Is it hot outside? When was the last time they had a chance to go outside to pee or poop?
I remember going to a dog park where a little 4-month-old Boxer puppy ran around jumping on everyone. The dog was not heavy enough to knock most of the adults down. However, it left everyone with muddy pants and the dog was big enough to knock over small children. The owner did nothing to stop the jumping puppy. After all, it was just a small pup. Everyone around her was pretty annoyed at the muddy prints the dog was leaving all over their clothes. That is an owner who will have a problem with her dog jumping on people when it gets older.