Clarify data model and and email sending

We are currently testing the plugin and have two questions regarding the plugins data model and email sending.

1. Does the plugin send transactional emails like confirmations and opt-ins via WordPress’ internal mail system when the *transactional email* feature is disabled? Our hosting just informed us that many emails are sent from the webserver after we added a subscription form. We assumed form data is submitted to brevo and all transactional emails are handled there by default.
2. Why does the plugin store email addresses submitted via the form in a custom database table? Wouldn’t it be sufficient to submit form data to brevo and handle data over there? If email addresses are stored locally in the WP instance, it needs to addresses in the site’s privacy policies and data handling procedures.

Thanks for clarifying!