edit: No sense guessing, apparently Kawasaki has used placeholder bikes in the past.
But I think jp website Young-Machine has a point -- ZX25R was introduced at a Japan moto show, and likely the ZX4R will be too, which implies Mar'23 or Oct'23. But if this is a USA bike not for Asia ...
Another post of "yes but when": It’s A Big Secret. Don’t Tell Anyone. The Kawasaki Ninja ZX4R Is Coming Stateside – SuperbikePlanet
But I think jp website Young-Machine has a point -- ZX25R was introduced at a Japan moto show, and likely the ZX4R will be too, which implies Mar'23 or Oct'23. But if this is a USA bike not for Asia ...
Another post of "yes but when": It’s A Big Secret. Don’t Tell Anyone. The Kawasaki Ninja ZX4R Is Coming Stateside – SuperbikePlanet