(POSSIBLE MAJOR SPOILERS)
New artwork for Avengers 4 leaked online. This could be elaborate fan-art, but the art style matches previous Marvel promotional material. The updated costumes also point to this being official instead of a fan posing all the characters together. While this is a “safe” piece that doesn’t spoil the plot of the movie, we can guess at a few details.
Black Widow’s hair tells time. Avengers: Infinity War’s blonde Widow is gone and replaced with the classic scarlet hair. The new hair supports rumors that Avengers 4 takes place “5 years” after the events of Infinity War. Therefore, if Avengers 4 took place immediately after Infinity War, Black Widow would not have time for a new hairdo.
Another measure of time is War Machine’s armor. The armor is a new design that appears even tougher than previous versions. It looks closer to the Hulkbuster armor than the more traditional suit Iron Man is wearing. Of course, Tony might have already had this in the works before Infinity War.