Why among the twelve emperors of the Qing Dynasty, Yongzheng, Jiaqing, and Daoguang, their names are different from the names of their brothers?

No, the name you mentioned is different because the royal family has regulations that the emperor's name should be a relatively uncommon character. If it is a commonly used character, it must be changed. This is the case for Jiaqing and Daoguang. Yongzheng and the Fourteenth Prince had the same biological mother, so they both had the character "Yin". The following emperors did not change, which was also related to the country's recession.