The Misunderstood Mischief questline tasks you to "make a new friend," but many players are having trouble completing it. It seems the questline may be bugged, causing the quest to not be completed even after adding a new friend.
How to fix Misunderstood Mischief quest issue in Pokémon GO
The easiest way to fix the issue is to contact Niantic customer support. Players have reported Niantic customer support fixing the issue fairly quickly while restarting/uninstalling does not seem to fix the problem.
Related: Pokemon GO Friend Codes (June 2022)
The first step to fixing the issue is to make sure you are correctly doing the quest. The Make a New Friend task is pretty simple, but it does require you to send a friend request, then have it accepted. If you have done this during the Misunderstood Mischief questline and it is still not completed, contact Niantic customer support.
How to contact Niantic customer support in Pokémon GO
You can contact Niantic customer support in the Pokémon GO app for a live chat to explain your issue. Open Pokémon GO and press the Pokéball at the bottom of the screen. Select Settings at the top right, then press the Help bubble in the top right of the screen. Next, select the chat bubble icon in the top right corner to start a live chat.
Describe the issue briefly and customer support should be able to help. The questline seems to be causing lots of issues, so customer support may be a little slower than usual.
Pokémon GO is currently in the middle of the Pokémon GO Fest, hosting live events around the world and offering new special research tasks. While you are waiting for the add friend issue to be resolved, you can take on other special research tasks or compete in one of the battle cups happening.
For more Pokémon GO guides, check out Pokémon GO: Shadow Pokémon List & Purifying Guide on Pro Game Guides.