Hi Michael, yes you need both XML Sitemap & Google News and Google News Advanced. Both plugins need to be activated but you only need the option “Google News Sitemap” activated on your Settings > Reading page. Now, you’ll have the advanced options available on your Settings > Google News admin page.
You may also activate the option “XML Sitemap” on your Settings > Reading but then you’ll need to make sure to disable the XML Sitemap in the Rank Math options. There will be an admin notice explaining the incompatibilities and what you need to do to work around them. You may also use the sitemap provided by Rank Math.
Whichever sitemap you choose, it should not impact traffic. An XML Sitemap is just a tool to help search engines find (new) content on your site. Once fully indexed, it will remain in the search engine results. If you do not add new content, you could even completely disable the sitemap and traffic should not be impacted. If you see a sharp drop in traffic, then it’s probably the new algorithm that is impacting your sites appearance in search results.
One thing though: be sure to NOT include any URLs in your sitemap that are set to “noindex” by the SEO plugin. For example, if you set taxonomy archive pages to noindex, then do not include taxonomies in the sitemap. Or if you give a particular page noindex, then also set it to be excluded from the sitemap.
You can use Google Search Console to monitor your sitemaps (both the normal and the news sitemap) for errors. And compare how many URLs provided by the sitemap are already indexed.