In May of last year we added logic to NOINDEX stream pages with minimal content.
In February we added tag pages with organic search to the sitemap
Now that google has tag pages in the sitemap, any tag page with less than 20 articles has a NOINDEX which confuses google. They are throwing errors because it doesn’t make sense to have a page in the sitemap but NOINDEX it.
We decreased the limit to only NOINDEX tag pages with less than 5 articles (to match story type/category pages logic) and this should take care of most of the conflict. We will address anything left on a case by case basis.