A simple utility that cold patches the Desktop Window Manager (uDWM.dll) in order to disable window rounded corners in Windows 11. Tested on build 22000.194.
To successfully patch and not brick your system, make sure you have only one dwm.exe process running. If you have multiple, connect normally to Windows, not using remote desktop or something similar.
Application requires active Internet connection when patching in order to download symbol files for uDWM.dll.
It is preferable but not mandatory to run the files from a separate directory. The app will temporarily place 2 files: uDWM.dll and uDWM.pdb in the directory they are in, overwriting any existing files.
Original uDWM.dll is backed up as uDWM_win11drc.bak in %windir%\System32.
Consult the source code if you want to patch manually, which is also quite advisable, it only takes changing a few bytes in the uDWM.dll file.
Please make a backup of the original uDWM.dll file before using so you can restore properly in case something is messed up. Use this software at your own risk.
To restore rounded corners, run the application again. After uninstalling, it is recommended to run sfc /scannow in an elevated command window to restore proper file permissions to uDWM.dll.