Having the link and the title agree, or be very similar, is good practice and provides continuity between the link ‘clicked on’ and the web page that the user lands on.
Some screen readers may read a document’s title in the iframe instead of the title attribute on the <iframe> element, if the document’s title is available. A best practice would be to use both a title attribute and the <title> element that matches each other to make sure the same title is read across various screen readers.
Accessibility (WCAG 2 Level A, 2.4.2), SEO, Usability
The checkpoint examines the entire HTML source code of a page and reports there is no <title> element found or if the title element is empty