TYPO3 Core

The HTML 5 specification defines <nav> as:

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links. Not all groups of links on a page need to be in a nav element only sections that consist of major navigation blocks are appropriate for the nav element. In particular, it is common for footers to have a list of links to various key parts of a site, but the footer element is more appropriate in such cases, and no nav element is necessary for those links.

The key phrase there is “major navigation”. A generated content element added by an editor will mostly be not considered as "major navigation". Therefor it can be replaced by a div element.