The hero who currently doesn't have a name appears to be holding a cannon of some sort which people on Twitter are speculating could be a healing turret, allowing you to place a turret down and heal any teammates who are running by.
The leak comes after Activision Blizzard canceled story missions for the game, after claiming that the entire reason that they needed to move from Overwatch 1 to Overwatch 2 was so that they could focus more on the story elements of the game. In a statement, the company had the following to say:
“With everything we’ve learned about what it takes to operate this game. It’s clear that we can’t deliver on that original vision for PvE that was shown in 2019."
The newest support hero for Overwatch 2 is supposed to release with Overwatch 2: Invasion, also known as Overwatch 2 Season 6, which comes out on August 10, 2023. This means that the character will probably be revealed soon and that you should keep an eye on Activision Blizzard's social media channels for announcements.