https://wrestlingworld.co/rumors/reason-why-ceo-harold-meij-left-njpw/ Per Dave, Meij had some pretty big ambitions for the U.S. expansion and NJPW as a whole, hoping to get revenue to $100 million. With COVID and the lack of a TV deal putting a nix on that, maybe that's why he's leaving.
Some are also speculating he was the biggest opponent to a working relationship with AEW. But I also don't see them doing that while still working with ROH.