In Mission: Impossible - Fallout, Ethan Hunt and August Walker tracked a guy in men’s wash room who got killed accidentally. He is not Lark, then who is this guy and how did he get the invitation band?
As pointed out by eduffy in comments, this character is decoy Lark. Medium.com
also, have nice details about the character and also provide the information that he is played by stunt actor Liang Yang .