Xuanqing has an incarnation permanently residing in the Buddha Realm, discussing Buddhist Law with Jieyin and Zhunti, and another incarnation has transformed into the Huiyue Demon Lord in the Demon Realm, establishing the Jie Sect and overseeing the Heart Demon Lineage. Having studied the Great Dao of the mind intricately, it is natural for him to immediately discern the flaws in Nezha's Dao Heart.
Moreover, from Zhu Zhao and You Ying, he acquired a fragment of the "Creation Jade Disc," which contains the profound mysteries of the Great Dao of the mind.
With an uncertain initial resolve, insufficient confidence, excessive caution, and difficulty in maintaining perseverance, coupled with his inherent demonic nature, these are the reasons why Nezha is susceptible to erosion by demonic energy.
"The human heart is ever-changing, but the Dao Heart remains steadfast. On the path of cultivation, there are too many temptations, and no one is always free from setbacks and failures!"