By searching the solution to disable shadows in MacOS, I found an answer defaults write com.apple.screencapture disable-shadow -bool true
But it does not work in the latest MacOS - Big Sur
How do I disable shadows of windows in MacOS Big Sur?
I've searched for years for something that works. As I use an inverted screen, the shadow is bright white and drives me nuts. This is the only thing I've found that comes close to working: https://github.com/w0lfschild/winBuddy
It is a bit flaky and messes up firefox tabs and ms office
If someone finds a better solution, pls let me know