Thanks for the request!
The app uses Google Analytics as well as Firebase performance monitoring and crash reporting. This can be disabled in the privacy settings.
Apart from that, it depends on how you use the app. Generally, 99% of status updates are fetched directly from the carrier without ever contacting my server.
An exception to this are carriers where I have to make sure my API access is used according to their terms (like rate limiting, ...) for which my server will act as a cache and may temporarily store the tracking ID and status messages.
If you use the device synchronization, all delivery data except passwords will be stored on my server (for both the Deliveries account and Google account options). This currently does not include the actual status messages.
If you use the Microsoft translation service in my app, all translations will be stored on my server to reduce the API usage for all future translations of the same text.
If you use the email token (recognition service), the emails you send to it will be stored up to a few months. In case you report an issue with the service, I may manually read and analyze them.