It appears that the error message indicates a conflict with the package name used in your app. Since this is a new app listing on your new Google Play developer account, you'll need to follow these steps to resolve the issue:

- Ensure that the package name (application ID) for your app is unique and different from any previous versions or apps associated with your old Google Play developer account.

- When uploading your app, make sure the build includes the updated package name (application ID) that you've chosen for this new listing.

- Verify that the Firebase project and any backend services also use this exact same Application ID to avoid any further conflicts.

These steps should help you successfully upload and publish your app to your new Google Play developer account.