This app literally collects nothing. No Ads either.
You supply your API key. It's stored on your device. It's never sent or stored on anything except your local device.
The ONLY thing collected is whatever email you provided so that you could be added to the TestFlight group.
If you downloaded the app from the App Store and are not part of this TestFlight group for beta builds, then there's nothing I have stored on you.
That's it. Yes it can be that simple.
Now what Open AI stores on you? I strongly encourage, you to read the data usage policy in the link below.
At least with API, your data isn't retained forever and not used to improve their models.
As an added benefit the data sent to Open AI via the API is kept for 30 days but not used to train their models
Does OpenAI store the data that is passed into the API?
As of March 1st, 2023, we retain customer API data for 30 days but no longer use customer data sent via the API to improve our models. You can learn more in the Open AI
data usage policy.