Something about moving to the Fall season brings with it lack of centering your attention. My advice to you is to go with it. Yup, don't fight it. Take a day or two to stare at the sky, read a book, socialize as best you can with friends, play your video game or watch MORE TV/movies. The only way to refocus yourself is to embrace it.
If you fight the lack of focus you will burn yourself out slowly. Everything you do, for work or personal, will take longer. Creating a presentation will go from taking an hour to two days. Cleaning out your refrigerator will take you a full day, with some of it just going back on the shelves for another day.
September brings with it the beginning to of shorter daylight hours and cooler evening weather. As that grows, October brings a mix of Fall and the start of Winter. So, if you don't allow your mind some freedom right now to wander and breathe you are in for a stifled end to your 2020.
2020 has not at all been how anyone thought it would be. We've all made the best of it, used it as a time to regroup, changed our priorities and learned to slow down. However, there are some things even COVID has no power over, that is Fall Brain. Don't fight it or get frustrated. Just go with it and it will pass much quicker so you can get back to business; Your career business.