According to expert analysis, Yongzheng is most likely to die from taking Dan medicine poisoning or having too much sex.
Poisoning by taking Dan medicine. Yongzheng had a close relationship with Taoist priests before his death. When he was a prince, he was very interested in alchemy. After he became emperor, he was still interested in alchemy and kept some Taoist priests in the palace to make an alchemy for him. Yongzheng not only took medicine himself, but also often gave it to his confidants, such as E Ertai and Tian Wenjing.
On the second day after the death of Yongzheng, Qianlong, who had just acceded to the throne, immediately expelled Zhang Taixu, Wang Dinggan and others from the palace, saying that they were street hooligans, and it was best to spread rumors, and all the blast furnaces and pills in the palace were removed from the palace.
It can be seen that the death of Yongzheng should be closely related to Taoist priests, otherwise at the beginning of Qianlong's reign, regardless of state affairs, the Taoist priests were driven away first.
Extended data:
According to the records of Sejong in Qing Dynasty, Yong Zhengdi fell ill on August 21st in Yongzheng, and was still able to work normally at that time, but died suddenly on 23rd, and the cause of death was never mentioned. Donghua Lu also recorded that Yong Zhengdi died in the Yuanmingyuan emergency, but the specific reasons were not mentioned.
The official did not announce the cause of death, and Yongzheng made too many enemies. There were many bad legends and discussions about him before his death, so the speculation and rumors of Yongzheng's natural death were widely circulated. The most popular folk story is that Yongzheng was stabbed to death by Lv Siniang, and there is even a ballad called "Lv Siniang stabbed to death Yongzheng", and Liang Yusheng also wrote this story into the martial arts novels.
According to folklore, during the Yongzheng period, due to the anti-Qing remarks in Lv Liuliang's works, the Lujia family was hacked to death with a door. Only Lv Liuliang's granddaughter Lv Siniang, who was only fourteen years old, escaped when the government raided.
In order to get revenge, Lv Siniang went into the mountains to learn from his teacher in anonymity. After ten years' hard training, she finally learned peerless martial arts and became a woman of great prestige. So Lv Siniang used what he had learned to sneak into the inner court of the palace, assassinated and cut off Yong Zhengdi's head.
In fact, this is just a novelist's words, so don't take it seriously. Lv Siniang is just a legend. Yongzheng disposed of Lu Jia. In addition to slaughter and beheading, Lv Liuliang's grandchildren were all sent to remote places as slaves, strictly controlled and unable to move freely, let alone avenge their ancestors.
References:
Baidu encyclopedia-Yongzheng