What triggers this issue?
This issue reports all internal page URLs of a website that return one of the 3xx (Redirection) HTTP status codes and receive some organic search traffic (as per data from Ahrefs’ Site Explorer).
Why is it important?
Most likely, the reported URLs were redirected recently. So this issue indicates that Google has not yet noticed the redirection and still shows these URLs in the search results. These pages will be removed from the search index only after Google re-crawls them (which may take a while).
If people click a link to the redirecting URL, they might end up on an unexpected page. This will provide poor user experience and can negatively affect the reputation of your website.
You should note that organic search traffic in Ahrefs is not real-time data, and search engines might have already deindexed the redirecting URL.
How to fix it?
Review the list of affected pages to see if they were redirected intentionally. If they were not, you would probably want to restore those pages.
For a large number of URLs, you should update your sitemap file and submit it to Google in Google Search Console.
Even if you don’t do that, search engines will eventually re-crawl these URLs and see the redirection.