Why are there so few Manchu people in Beijing, the capital of the Qing Dynasty?

After the Qing Dynasty made Beijing its capital, all the immigrants to Beijing were nobles and dignitaries. In fact, the population is not large. Later, during the Revolution of 1911, many Manchu people changed their names for fear of persecution. Worried about settling accounts afterwards. After all, there was a rejection of Manchu in the whole country at that time. Although the top level has not changed much. This is not the case at the bottom and middle levels.