Read this document to understand how the app Syncthing-Android uses data and respects user privacy.
Syncthing-Android values user privacy and thus does not collect any user information.
For location data includes very sensitive personal information related to user privacy, the app does not store any location data. The permission to access location in the background is used only to check for an SSID of the currently active Wi-Fi. The sole purpose of this information is to limit synchronisation to user-configured Wi-Fi connections. At no point is this information used to determine the user's actual location nor is it ever shared with any 3rd party entities.
The permission to access camera is used solely to scan QR codes in order to provide an easy method for entering device IDs. The app does not save any pictures or video in the process.
The app runs Syncthing, which may collect anonymous usage data if the user consciously opts in to it or decides to run beta/condidate builds. Specific information on the anonymous usage reporting is available under https://docs.syncthing.net/users/security.html.