WTF happened on BTX blockchain or qt client?

I sent 4 BTX from windows desktop qt client.
bitcore-qt client transaction show: -4 BTX:
https://drive.google.com/open?id=15ouQMRIevFnuN66qx24SLcBpV0r1v0cH

BTX block explorer show: -20 BTX: -4 BTX to my deposit address and -16 BTX to unknown address
https://drive.google.com/open?id=1n8ulnPOXFPkFupjwy8-kmzKumVIU7naE

And the balance not equal in qtclient and block explorer.

What happened?