Because she noticed that Queen Mother of the West's self-corpse avatar was named Liu Ling, and names for avatars were never chosen at random—much like Qingling Celestial Venerable's three external avatars.
One was a Divine Sense avatar borne by the top-tier Xiantian Spiritual Treasure gourd, the Purple-Green Gourd. Named Daoist Ziling, he currently sat in the Ziwei Enclosure, exercising actual control over the Zhoutian Star Formation as Emperor Ziwei, one of the Six Sovereigns.
Another was a Divine Sense avatar borne by the top-tier Xiantian Spiritual Treasure, the 12th-Grade World-Destruction Black Lotus, straightforwardly named Black Lotus Daoist. The final one was borne by the Chaos Spiritual Treasure carrying Qingling Celestial Venerable's self-corpse Divine Sense—the blade of the Pangu axe. He used the name Daoist Zhang Qing, which was the name he used before his transmigration.
Chapter 373