Marvel has settled most of the fight over the copyright of their iconic characters. The fight which began in 2021, started a series of lawsuit over the copyright of many Avengers characters. Although they've reach an agreement, the fight isn't over yet, per The Hollywood Reporter.
In 2021, Marvel was issued copyright termination notices from Larry Lieber and the estates of Gene Colan, Steve Ditko, Don Heck, and Don Rico. In response, the company filed a series of lawsuits. They argued that US Copyright Law doesn't cover works made for hire.
As for Larry Lieber and the estates, they filed the termination notices because U.S. Copyright Law gives authors or their heirs the ability to get back copyrights after a certain period of time. Some of the titles under fire are: Amazing Fantasy, The Avengers, Captain America, Daredevil, Iron Man, Journey Into Mystery, Marvel Super-Heroes, Strange Tales, Tales to Astonish, Tales of Suspense, and Tomb of Dracula.
As well as art and stories from the comics, the termination notices also targeted “any character, story element, or indicia reasonably associated with the Works.” So that has included Avengers like: Iron Man, Captain America, Black Widow, Hulk, Thor, Hawkeye and Scarlet Witch.
Marvel has reached an agreement with them, and the parties have filed joint stipulations for voluntary dismissal. But, there's still one problem. The late co creator of Spider-Man and Doctor Strange, Steve Ditko, hasn't filed a notice of termination. Thus, the fate of Amazing Fantasy and Strange Tales has yet to be determined.