Google has revealed it no longer supports the meta news keywords tag, and hasn’t supported it for several months.
It wasn’t until Joost de Valk of Yoast asked Google’s John Mueller about the meta news keywords tag that we got any kind of official word.
Hi Joost, it looks like we dropped support for this around the time when we removed it from the help center. Keeping it on pages is fine, we just don't use it for Google News anymore.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) February 20, 2018
Considering the tag hasn’t been supported for months, and the change is just being noticed now, it should be an indication of how many site owners used the tag on their news articles.
The low adoption rate could be the reason why support for the meta news keywords tag was dropped. However, Google did not specifically say why support was dropped, so we can’t confirm this.
It will not do any harm to keep the tag on news articles, Google will simply ignore it like it does the regular meta keywords tag.
So if you have the tag in place already, don’t worry about it, just don’t go out of your way to add it to any future articles.