Of course it's true. When Queen Inhyeon was dying, Zhang Xipin put an archery curse on the portrait of Queen Inhyeon in the west hall of Shantang in Chang Gung Palace. The arrow pierced Queen Inhyeon, which made the wizard curse Queen Inhyeon, and instructed the maid-in-waiting to bury the ashes of dolls, sparrows, mice and dead children and the phoenix clothes of the queen in the backyard of Dazao Hall in Changde Palace and Tongming Hall in Changqing Palace respectively. On August 14th, the 27th year of Su Zong, Queen Inhyeon died in the Palace of Jingchun in Changqing. Because Shu loves Cui Shi (Yingzu's biological mother), it was revealed to the world. Su Zong personally interrogated the ladies-in-waiting of Changde Palace and put them all to death. These are clearly recorded in the memoirs of General Su, not in Du's film and television works.
Zhang Yuzhen, the prince's biological mother, wouldn't have committed suicide if she hadn't committed a heinous crime.