I am an EU resident. I eventually managed to find it by following the link in the email while signed in to FB, and sent a generic message that I don't trust AI to not misinterpret or leak my data, while also stating that I consider AI training to be by design a breach of my GDPR rights, since there is no way for them to delete your data from the AI once it has been trained on them, which the legislative hasn't caught up to handle yet, since AIs are kind of new and nobody expected that. It worked pretty quickly, and I should be opted out now