Do Han Chinese who worked in the Ministry of Internal Affairs in the late Qing Dynasty have to join the banner and become Manchus?

No.

The Ministry of Internal Affairs of the Qing Dynasty was a very large organization. In addition to being responsible for handling various living expenses for the royal family on a daily basis, he also manages the royal family's fields, real estate, forest products, and paddocks. Run royal factories such as weaving factory, mine, clock factory, glass factory, paper factory. He made horses, weapons, and entertainment supplies for the royal family, and managed Taiyuan Hospital and Taipu Temple. Rewards to the clan, ministers, and local princes. Manage gardens, palaces, ancestral temples, royal temples, organize various sacrifices, ceremonies, etc.

Some of the personnel registered with the Ministry of Internal Affairs are in the flag, and some are not in the flag. Most of those who are not in the flag are hired staff, various craftsmen, and businessmen who have contracted the production.

Many of the people in the banner are managers and officials at all levels. Of course, the lower-level gardeners, livestock attendants, imperial doctors, horse trainers, deer workers... are also in the flag.

In your situation, the painters of the Royal Academy of Painting can be in the flag or not. Painters who are in the flag are on a tenure-track basis, while painters who are not in the flag are on a hiring basis. The painters in the banner have the same treatment as the resident officials. The official rank is from the third rank and the salary from the third rank. At the same time, they can also receive the Eight Banners' food and salary, and have the right to be summoned directly by the emperor to paint. The hired painters who were not in the banner had the official title of fourth rank, and received only the salary of fourth rank, and no other treatment. They could only enter the palace to paint under orders from the Ministry of Internal Affairs, but did not have the right to be summoned directly by the emperor.

The painters on the flag are different from those when the Manchu soldiers of the Eight Banners joined the flag. In the past, the ministries were not unified. Nurhaci unified the ministries through force. At that time, many tribes were forced to join the banner. But there was no Ministry of Internal Affairs at that time. It was not until the Emperor Taiji period that the Ministry of Internal Affairs began to take shape. At that time, painters were recruited into the banner with preferential treatment, rather than forced. Later, when the Qing Dynasty entered the customs, the scale of the Ministry of Internal Affairs increased, and a considerable number of people joined the flag, such as: architects, hardware workers, winemakers, imperial doctors, porcelain workers, book offices, painters... These people were recruited voluntarily. Flag, which is similar to today's employees in the state-owned sector. Later, the Eight Banners establishment was full, and in order to make up for the shortage of manpower, they recruited people outside the establishment, which was similar to contract workers.

In short, joining the flag is either compulsory or voluntary. The specific circumstances are different and cannot be generalized. Not all the Han troops in the Eight Banners were originally Han Chinese. Not all the Eight Banners in Manchuria were Jurchens back then. Not all the Eight Banners of Mongolia are Mongolian. Not all Han people in the banner were forced to join the banner, and not all Jurchens in the banner joined the banner voluntarily.

You’d better ask the Manchu people this kind of question. If you ask the Han people online, most of them won’t understand.