He realized that he should have paid more attention to the fact that a treasure that was so valuable had just appeared within the vicinity of New Swampscott City. Yet, it was only detected after it bloomed. With such an attractive treasure in their territory, Yoze would have thought that the City would have long seen its existence and set up barriers to harvest it in peace.
After the treasure was harvested, the City could use it for their means or even use the treasures they collected to hire rogue immortal cultivators and witches. This could explain how he had difficulty detecting the spiritual energy and presence of all the prison guards and prisoners when he visited the prison.