Hello @Knowledgecity
Thank you for reaching out in relation to Our Domain Validation process. To first answer your question, it could be that a under app listing is using that specific domain, it could have to do with the tutorial you have added. If you want to proceed and include that url, the next steps will be sent to you via DM. Please refer to our domain validation resource: Domain Validation Explanation for any further questions you may have about the process.
Thank you.