Citation issues are all the errors that might happen in your site's history, like duplicate content, broken links, and more. Cleaning up these citations is important for SEO because they can negatively affect your site's ranking.
Citation cleanup in SEO refers to the process of fixing the potential errors that might be in your site’s history.
The most common citation error is duplicate content. For example, you have two articles on the same topic on your website and neither one has a link to the other one.