While that role isn’t named at this moment, there’s a pretty good guess who Yahya Abdul-Mateen II is playing; especially when factoring in the return of Reeves’ Neo and Moss’ Trinity.
Previously known as the big screen version of Black Manta in director James Wan’s DC Comics picture, Abdul-Mateen II apparently rose to the top of an intense casting blitz that saw Wachowski choosing him for a lead role in The Matrix 4.