Your app could be getting rejected due to incomplete purpose strings.
A "purpose string" is a short message or description that explains to the user why an app needs access to a specific feature or resource on their device, such as their location, camera, or microphone. These strings are displayed when the user is prompted to grant permission for that feature.
If you find that when requesting a device resource in your mobile app, you're seeing a popup with incomplete purpose strings or text such as [insert use case], then we'd recommend making sure that your purpose strings are completed.
These purpose strings are set in the Languages tab of the editor.
To set these purpose strings, you can edit the App texts in the Languages tab of your app’s settings. The relevant strings will be at the bottom, prefaced with MOBILE:
You’ll want to make sure these purpose strings are descriptive and specific to your app to get approved by Apple.