Health regulations have been circulating. First, because the mobile phone network is not good, the health code declaration needs the network. Bad network will lead to no results. Second, too many people use it.
It's usually a network problem. You can switch to mobile traffic and reload. It may be that your mobile phone software has a small memory, which causes the phone to get stuck. Then, there are many people around who use health codes at the same time, and the system is at its peak and loading is very slow.