If that is the case, then the AI was also correct, and you need to add the TXT record as specified here:
https://answers.netlify.com/t/support-guide-another-site-is-using-this-domain-verifying-domain-ownership-for-netlify-production-domain/13765?utm_content=ask-netlify
The value you would use is:
https://answers.netlify.com/t/need-control-of-my-domain-within-my-netlify-account-but-it-is-under-teesprings-control-and-they-dont-understand-how-to-respond-to-my-request/123634