Its definitely a loop. He contacts the ball with perfect timing and sinks the ball into the wooden layer. A very hard loop sometimes has a very "hard" clicking sound like the smash
This is one of those things I believe is more of a motion natural to the penhold type of play vs shakehand. Like the super big fh you see XX make were he bends over backwards and just let the arm rip! ML is more of a surgen close to the table imo and the move you reffer to is his way surpricing the opponent instead of letting the ball back and then rip in to it. (Sure, he does that too)