The author's registration date

Hi everyone! Please tell me how to get the date of user registration.
frontity.state.source.author[id] has no such endpoint. Thanks!

If you have a specific question or need information about a particular author, I recommend checking publicly available sources such as the author’s website, social media profiles, or biographical information provided in their published works. If the author’s registration date pertains to a website orthokeratology doctors Glendale or online platform, you may need to contact the website administrator or support team for that specific information.