This twitter account has been covering china's lockdowns pretty extensively. The covid tracking app they have is used to get into various things in a city like malls, transportation, etc.

For some reason the app in the video looks to me like it's a bit different to the modern app, but this video is from the start of 2022.

This is how it works since February 2020 in china.You need to scan it everywhere you go.💚you can move freely.💛you can't take public transportation and get in public places.❤️you need to call authority and will be quarantined under government's watch. pic.twitter.com/rH4InKB1ew