“Failed to initialize BattlEye Service: Windows Test-Signing Mode not supported.” error

Please disable test-signing mode by following this guide from Microsoft:
How to disable the "Test mode" message that is displayed in Windows (Відкриється в новій вкладці)

Alternatively, you can follow the manual instructions from Microsoft here: Enable Loading of Test Signed Drivers (Відкриється в новій вкладці).

If you're using hardware that requires driver signature enforcement to be disabled, check the vendor’s website for newer drivers.

Unfortunately, since BattlEye's goal is to provide the most effective protection possible, they cannot support systems running in test-signing mode in any way.

For more information, see BattlEye's official FAQ here (Відкриється в новій вкладці).