If this is a typo, Kangxi won't let it hang on the door openly. Worst of all, he should quietly change the correct plaque at night. How can everyone see this strange thing? Cixi wrote the word "Fu" in those days, because it was a bit too much. Li immediately reminded her that Cixi quickly wrote another letter.
Kangxi was an emperor and received orthodox education. His calligraphy teachers were all human beings. How can he write such words? In fact, there are many ways to write the word "taboo", and it is ok to add one more. Many famous artists, such as Mi Fei and Zhao Ziang, have the word "taboo" in their calligraphy works. Gan Long also wrote a picture of Watching Fish in a Flower Harbor, and there are only three points under the word "fish".
Kangxi may have used this typo to test the loyalty of courtiers. Zhao Gao was in charge of state affairs and wanted to test whether ministers were willing to support him, so he took a deer to Qin Ershi and said it was a horse. Qin Ershi said with a smile, this is obviously a deer. Some ministers said it was a horse, while others said it was a deer. Zhao Gao secretly wrote down the ministers' answers, and then tried to kill those who said they were deer. Kangxi may also want to use this method to test his subordinates. They knew Guan Qiao and naturally wouldn't point it out.
Others said that Kangxi thought the word "avoid" had the meaning of avoiding the world, so in order to avoid the world, he deliberately wrote one more line, just like the ancients wrote their parents' names wrong to avoid names.