I do business with Chinese contract manufacturers and have WeChat installed to communicate with them. Can you tell me what the app is doing on an iPhone when it

I do business with Chinese contract manufacturers and have WeChat installed to communicate with them. Can you tell me what the app is doing on an iPhone when it's either in the background or not running at all? My assumption has always been that communications over WeChat are accessible by the Chinese government, but is there more to it than just that?