Your puppy is still in the teenage phase and may be rebelling a little. During this time, it might be a good idea to remind your puppy of everything that it has learned. Continue to work on recall, leash walking manners, and basic obedience. Be consistent. The chewing behavior may also come back again. Provide your puppy with lots of sturdy chew toys and bones. Accidents may also reoccur because as their brain enters the teenage state, your puppy may forget things and need lots of reminders of what is and is not appropriate. Make yourself aware of this too.
Mental stimulation would be a great idea.
Mental stimulation is still important to a dog’s behavioral well-being as physical exercise. Since most domesticated dogs receive their food from out a bowl on a schedule, they are deprived of the mentally stimulating foraging activity natural to them. Offering outlets for these natural behaviors can drastically reduce problem behaviors that are going on in the home.
Also, socialization is super important during this phase. You don’t want your puppy to develop any reactivity towards other people or dogs. Socializing with other dogs and people is always a positive experience. If there is anything that negatively happens, remove your puppy from the situation and give them a break. After the break, you can then revisit the other people or dogs.
If you notice separation anxiety in your puppy when you leave them at home alone. It is best to address this issue before it gets worse.
Read more here: https://www.amysmtndogtraining.com/post/separation-anxiety
At this age, you should do the basic Obedience Class or a Canine Good Citizen class with your older puppy.
Classes can be found here: https://www.amysmtndogtraining.com/groupclasses