There had been many factors involved in Sakura breaking free from Chiyo's Blood Dragon Eye Illusion.
After someone fell under a genjutsu, changes in the surrounding environment could have a major effect on them as well.
Just think about it. Ever since Sakura had fallen under Chiyo's Blood Dragon Eye Illusion, how intense had the fighting around them been?
Then there was the fact that after Sakura fell under the genjutsu, she had inhaled quite a bit of poisonous flower pollen when Reanimated Hashirama Senju used Flower Tree World Descent.
It was practically fighting poison with poison!
Moreover, after Chiyo used the Blood Dragon Eye Illusion to control Sakura, she had merely treated her as a hostage to force Sasuke into fighting her.
So afterward, Chiyo had summoned the Nine-Headed Blood Dragon and used her Ketsuryūgan's power, combining her own blood with the blood orb Soji had given her, to summon Blood Shadow Soji.
That alone had been an enormous drain on Chiyo.
When the caster entered a weakened state, the person under the genjutsu had more room to resist.
In other words, Chiyo had believed her genjutsu control was foolproof and had not continued strengthening her hold over Sakura afterward.
Finally, Sakura herself had always possessed an exceptional talent for genjutsu.
This had been mentioned more than once in the original story.
It was just that the original Sakura had no way to learn genjutsu, so she developed that talent in dispelling genjutsu and improving her resistance to it.
Therefore, although Sakura, who already possessed extraordinary genjutsu talent, had fallen under a Blood Dragon Eye Illusion that ranked even above a Three-Tomoe Sharingan illusion—
With all those factors combined, she had actually broken free from Chiyo's genjutsu on her own!
It really had to be called a coincidence!
Had