The preview for My Hero Academia Season 6 Episode 10 indicated that Deku falls on his anger and hits Shigaraki, whose regenerated face resembled his mentor, and after him the green hero will find himself in the realm of OFA vestiges.
My Hero Academia Season 6 Episode 10 Recap

After Bakugo throws Deku out of harm’s way, he’s injured by the oncoming rivets and falls to the ground. Meanwhile, Shigaraki, possessed by One for All, rejects Bakugo’s sacrifice as useless.
Deku has a flashback of Gran Torino being viciously beaten by the villain, and his childhood buddy is now seriously injured. Of course, he gets irritated and loses control. Deku jumps at Tomura, smashing all the rivets thrown at him.
When he has closed the gap between himself and the villain, Tomura grabs his face with his palm and tries to steal the Quirk One for All. But, for some reason, both find themselves within One for All.
Meanwhile, Gigantomachia follows his master, destroying everything in his route. Pro-heroes tasked with the evacuation are encouraged to abandon all tasks to stop the big monster.
Himiko Toga chooses to get off Gigantomachia’s back and confront Ochacho when she discovers that she is near him. Ochaco, concerned with the evacuation efforts, is approached by an elderly woman asking for help.
When Ochaco follows her through an isolated alley, the lady disappears, and it’s revealed that she is Toga. Ochaco continues to follow Himiko to confront her, only to be crushed to the ground by her. That’s when Toga asks about Twice’s death and how far the heroes are willing to go to stop them.
My Hero Academia Season 6 Episode 10, Ending Explained: Why does One for All believe that Deku is no good for One for All? Is Izuku dead?

Deku finds that his body is too weak to move after being trapped inside One for All. Nana Shimura abruptly strokes his head as a comfort and advises him not to strain himself too much.
Shigaraki approaches him carefully, One for All coming out of his shoulder. Then One for All reveals to Shigaraki that his dead grandmother is present with Deku.
The villain would have recurring dreams about people whose quirks he had stolen over time. These dreams only ended once he regained control of the powers he had taken. It was when he met Garaki that he realized what was happening. It turns out that organs and cells have memories too.
So, when One for All took someone’s powers, the quirk genes carried their knowledge. This could be a compelling discovery and will also explain Deku’s nasty nightmares, since he got his quirk from others.
When One for Everyone sees Deku in his vulnerable position, he mocks him and claims that he’s not worthy of All for One. However, One for All’s stubborn brother, who mysteriously appeared there, rejects his demands and supports Deku, declaring that the little boy deserves power as he’s willing to go to any extent to help others.
His attitude sets him aside from others. While Nina Shimura and Yoichi Shigaraki stop Tomura from destroying the planet within One for All, Deku gets to his feet and jumps for his enemy.
After Deku and Shigaraki escape from All for One, they can no longer fight and gradually collapse. Deku realizes that Shigaraki cannot remove his quirk, but he lacks the strength to fight his enemy. Suddenly, he starts falling from the sky, and his eyes close.
While some fans may have expected the worst, he lost senselessly. It’s normal not to expect him to die because, as mentioned in the early episodes, ‘My Hero Academia is Deku’s journey to become the greatest hero.