The Marvel fans who pay attention to details and stick around for the famous post-credit scenes will know that Nick Fury has indeed already been a Skrull at one point in the MCU.
Those who have seen Spider-Man: Far From Home know that the film features Mysterio as the main villain, using old Stark tech to conjure fake villains known as The Elementals throughout the movie before revealing himself as the villain for a big battle in London. Fans of Marvel might have been wondering how on earth something like that tricked Nick Fury and Maria Hill and the post-credit scene for the movie answered that question.
After the credits, Hill and Fury are seen in a car for a few seconds before turning back into their Skrull form, revealing they had been Skrulls for the entire length of the movie. “You gotta tell him,” says Soren to Talos, who responds “It was fine, the little boy handled it”, referring to Peter Parker. Eventually, Talos gives in and calls Nick Fury, relaying the events of the film to him and saying that he gave Parker Stark’s glasses as he wanted. When we cut to the real Fury, it’s revealed that he is on a Skrull spaceship somewhere unknown, overseeing construction.
When asked about what this meant and how long Fury could have possible been a Skrull for, director of Far From Home Jon Watts said that he thinks the real Nick Fury was at Tony Stark’s Funeral in Avengers: Endgame, which was comforting for many fans.