Lang attribute.

For blind users, the lang attribute is the one that commands our screen readers to automatically change the language of the vocal synthesis when reading the text in the tag that have its lang attribute assigned.

In the title tag, even inside an iframe, it is not commun to assign a lang attribute because it is generally settle in its parent tag.

But anyway. Too much information is better than nothing.

The "lang" attribute indicates the language of content within HTML elements like "HTML," "head," "body," "p," and "div." In contrast, the "title" attribute offers additional information or tooltips for elements like links and images.