The reason why Yongzheng gave Nian Qianyao to die was not simply because of a typo, although Nian Qianyao was severely reprimanded by Emperor Yongzheng for writing a typo in the recital, and became one of his crimes, but this was only the surface fuse.
There are deeper political reasons behind Nian Qianyao's death:
Meritorious and Powerful Masters: With his outstanding military talents and military exploits, Nian Qianyao gradually accumulated extremely high power and prestige in the Kangxi and Yongzheng dynasties, posing a potential threat to the imperial power.
Political ambitions: Nian is rumored to have imitated the emperor's actions in his personal life, such as flopping to select concubines, which are believed to be a suspicion of peeping on the throne and violating royal authority.
Forming a party for personal gain: Nian Qianyao and his family were so powerful that they formed the so-called "Nian Group", which was regarded as a party for personal gain in feudal society, which seriously violated the way of the monarch and the principle of exclusive imperial power.
Provocation of Imperial Power: Nian showed an arrogant and rude attitude in dealing with the imperial court, including his inappropriate words and deeds in the recital, especially the famous typo, which was regarded by Yongzheng as disrespectful and provocative to the imperial power.
To sum up, Yongzheng's death was a general outburst of many dissatisfaction and suspicions accumulated over a long period of time, and the typore was only the last straw that broke the camel's back, not the root cause.