cngit.exe: which program is it?

cngit.exe is a normal part of 中文Git when it sits in the program's install folder and carries the publisher's digital signature. A file with the same name in another folder can be something else: check its signature and hash.

By default the installer puts it in %ProgramFiles%\Chinese_git. The folder can be changed during installation.

Uninstall 中文Git through Settings → Apps or with winget; the uninstaller removes cngit.exe with it. Deleting the file alone leaves the rest of the program behind.