Separation related problems and anxiety around unfamiliar people, dogs and environments are currently seen frequently in adolescent puppies which were acquired during the first lockdown.
With limited access to the outside world and owners staying at home, many puppies were raised undersocialised, untrained or became over-attached to their owners. Puppies arriving in new homes during the current lockdown may face the same problems. Dogs are more likely to worry about things they haven't come across or had negative experiences about during the first 4 months of their lives.
The great news is that you can use the current situation to your advantage. Strangers won't overwhelm your puppy with their affection and many other dogs will be on leads, so your pup won't learn to jump at every person or expect to play with every single dog it meets. You have more time to dedicate to training and teaching your pup that other dogs and people are safe, but generally boring, i.e. nothing to get excited or worry about.
Socialisation is exposure with positive experiences and it does not have to be an interaction. Reassure, feed and play with your puppy, but never force interaction with something they are not yet comfortable about.
Make sure all your household share caring responsibilities as well as handling and playing with the puppy.
Introduce various household and outdoor sounds. Increase distancing if your puppy is worried and gradually build up the intensity of sounds.
Allow them to watch various types of traffic, bicycles, joggers, prams, people with hats, rucksacks, walking sticks etc. from a safe distance. Walk them in a variety of weather and at different times of day.
And don't forget that your puppy needs lots of time to sleep and relax.