Health codes are based on actual data and can be generated by citizens or people who have returned to work through online declaration and background audit. As an individual entering and leaving electronic certificate locally, the QR code can be declared once, which is universal in the whole city.
The color may change, depending on where you go. It depends on the risk area. If you go to the middle and high risk areas, the color of the health code will change. However, if you go to a low-risk area, the health code will not change color. Now most parts of the country have been lifted, so most parts of the country will not change color.