Avengers: Endgame was a culmination of many story threads cultivated in the Marvel Cinematic Universe over ten years. But for all the conclusions the film included, some impressive moments redefined the universe's power levels. That was shown best with Scarlet Witch nearly killing Thanos, but a new theory may have added Carol Danvers' standoff against the Mad Titan as another example of incredible strength.
According to the theory. Captain Marvel's ability to keep Thanos from snapping had nothing to do with the latent strength she had from her powers. Instead, it was her power's ability to siphon off energy that made her able to face off against him. That implied that it never had anything to do with her physical strength but also brought to light a power that was well-defined in the comics but barely explored in the films.
In the books, Carol's real power is that she can absorb energy and redirect it or use it to sustain herself. That was why she could go binary when she absorbed enough power. It also explained why she was nearly invincible during some decisive battles. However, in the MCU, this ability only got teased throughout her first solo outing. A great example of this was when she took out her inhibitor chip. After years of storing energy from battles, she finally cut loose and unleashed her full strength. But by Avengers: Endgame, it's implied she had finally gotten a handle on that aspect of her power.
The YouTube breakdown showed this when she grabbed the gauntlet from Thanos before he snapped. For anyone else that used it, the Infinity Gauntlet would glow because of the gems. However, when Carol grabbed it, the glove was no longer illuminated. That's because she was pulling energy from the Stones to give her a power boost, which also explains why she didn't flinch when Thanos punched her.
Should the theory be true, it may be the most definitive look at how her powers work and show how strong she could be should the power source she borrowed from be strong enough. Not only would this make her potentially the strongest Avenger, but it also showed that Carol was never afraid to take as much power as she could to protect innocents. Even more impressive was how the radiation the Stones gave off had no effect on her, meaning she could likely power through even worse, should the need arise.
There's no confirmation that this is the reason why Carol could hold off Thanos. But in terms of faithfulness to the source material, it's a clear explanation. It also showed that she can't always be that strong as there may be times when she would have to fight at her base power level, which is strong but not strong enough to face Thanos with the Infinity Stones. Nevertheless, the theory helped showcase that Captain Marvel is still the MCU's ace in the hole in terms of power.