I think I’ve found it: do you mean this part?
https://plugins.trac.www.ads-software.com/browser/contact-form-7-campaign-monitor-extension/trunk/lib/functions.php#L241
It looks like it would append this to emails.
<p class="wpcf7-display-none">
Contact form 7 Campaignmonitor extension by
Renzo Johnson
<a href="https://renzojohnson.com"
title="Renzo Johnson - Web Developer - Orlando Front end Developer - Full Stack Developer - contact form 7 - contact form 7 mailchimp - mailchimp for Wordress"
alt="Renzo Johnson - Web Developer - Orlando Front end Developer - Full Stack Developer - contact form 7 - contact form 7 mailchimp - mailchimp for Wordress"
target="_blank">Renzo Johnson - Web Developer - Orlando Front end Developer - Full Stack Developer - contact form 7 - contact form 7 mailchimp - mailchimp for Wordress</a>
</p>
@rnzo Can you confirm that to be the case? Powered by URLs are allowed unless the plugin user explicitly activates it. It has to default to off.