The utilization of any superpower will make AP particles fluctuate. Each superpower fluctuates differently.
If one could perceive the fluctuation of AP particles in advance, they could understand the opponent's superpower and prepare a counterattack beforehand.
However, these fluctuations of AP particles are extremely subtle, and auxiliary superpowers, like invisibility and metamorphosis, create even weaker fluctuations that are almost impossible to detect.
Of course, top-level power users and a rare few people with extremely strong perception can detect surrounding AP particles' fluctuation if their attention is highly concentrated.
Yang Fei is one of the latter.
She is not a genetically modified person and she has no superpowers. But she possesses the ability to invalidate AP particles.
Since all superpowers are exhibited by manipulating AP particles, invalidating these particles means that Yang Fei can annul all superpowers in the world.