"usingComponents": {
    "i-icon": "/component/icon/index",
    "i-modal": "/component/modal/index",
    "tabbar": "/component/tabbar/tabbar"
  }

the problem now is:

app.json can be used in developers" tools and debugged on real machines, but they cannot be used when uploaded into an experimental version and tested by mobile phone code scan.

must be introduced in page.jsonli to use

this situation was just discovered today. Have you encountered it?