Hi Vicki,
That date is the date the plugin was originally published, not the last update date. It’s still a relatively new extension, but I have updated it twice since its release, and it’s working just fine with the latest versions of WordPress and PHP 8.2.10.
Note that the plugin itself does NOT do the actual sending of emails. Just like the main plugin, this plugin uses the WordPress wp_mail function to actually send the emails. If you are using a plugin that replaces the wp_mail function to connect with a better email SMTP service (highly recommended), then it should still work fine as long as that plugin uses the same parameters and header formats that the wp_mail function uses. I haven’t test specifically with Brevo, but if it’s working fine with the free volunteer sign up sheets plugin, then it should work just fine with this extension.