If you have figuring out a way on how to disable Knox security system, you will have to flash a custom kernel on your Samsung Galaxy Z Flip 3. This will disable the Knox, implement Wireguard, kAdaway and supports KCAL.
This custom kernel for Z Flip 3 also implements KLAPSE 5.0, Boeffla Wakelock Blocker and Westwood TCP Protocol is enabled by default. Kernel is Permissive now. Keep in mind that this custom Z Flip 3 kernel works only with GSI and on Android 12. If you are on Android 12.1, it will cause a boot loop.
You can download Samsung Z Flip 3 custom kernel from here. Make sure to do a clean install if you face any battery drain issues. Some users pointed out that this custom kernel is causing excess battery drain. But this issue slithered away once they did a complete factory reset followed by refreshing of the custom kernel. Now, it is draining around 1.1-percent every hour.
Also, warranty is void the moment you flash custom firmware or kernel on your Samsung android device. But on bright side, no more Knox which can get in way if you are trying to perform modifications on your Z Flip 3.