Mac users upgrading to Big Sur are affected by this bug, and user reports about it have existed since July on Apple's developer forums. https://developer.apple.com/forums/thread/651131 If you use external displays, I'd hold off upgrading
This has definitely also been a problem with at least Catalina. I have a 49 inch curved monitor and plugging my MBP into it after using it on the go makes everything go to the southwest corner. Not that egregious but certainly a PITA.