UPDATE 27/5/23: In a report released in the aftermath of Naughty Dog's statement, Bloomberg's Jason Schreier has shed additional light on the behind-the-scenes decision-making currently impacting The Last of Us multiplayer game.
According to Schreier, development on the long-in-the-works title has "slowed down" after Destiny developer Bungie - which has been individually assessing Sony's many "games as a service" projects since its was acquired last year - raised concerns about The Last of Us multiplayer's "ability to keep players engaged for a long period of time".
As a result of this feedback, the Naughty Dog team working on the Last of Us multiplayer project is said to have been "scaled back", leaving only a "small group" on the project while Sony re-evaluates its direction. Bloomberg's sources say the game isn't cancelled, but that many of its developers have now been moved to other projects.