Or rather, it stems from Zheng Yi's powerful Core Formation Stage Divine Soul's perceptive ability.
Precisely because his Divine Soul is exceedingly powerful, it can still be suddenly influenced by this mysterious aura, subjected to intense pressure and intimidation.
Conversely, if it were an ordinary Foundation Establishment Cultivator, or even a Purple Mansion Cultivator, they would only feel some unease for a moment, without understanding where this pressure comes from, and would not be greatly affected.
As for the other creatures living throughout the Sumeru Forest Cave Heaven, such as ants, birds, and small beasts, they are entirely oblivious and unaware, incapable of sensing any anomaly.
In other words, the stronger the power, the higher the degree of spirit, the greater the intensity of the Divine Soul, the more sensitive, they would be affected by the sudden surge of aura pressure.
