Gary Illyes from Google said that in some cases, Google may not fully render a page before showing it in Google Search or Google News. It depends on how timely that content is and how quickly Google needs to index and serve it in Google Search.
That does not mean Google won't render the page fully, it will, eventually. But if a story is breaking and Google wants to show it in Google Search within minutes of the story being published, Google might have to come back later and fully render it later. Immediately, Google might process the HTML and then come back and render the page later to better understand the page.
Here are those tweets from Gary Illyes on this topic:
it's a bit more subtle than "news doesn't render". when you need to index fast, you need to have tighter deadlines and that might mean, for example, that we end up with the raw HTML in serving for a few minutes. It she's eventually fixes itself, but still
— Gary 鯨理／경리 Illyes (@methode) March 23, 2023
This is a small technicality, but yea, eventually Google will make an effort to render the page and Google is not slow at doing that.
Forum discussion at Twitter.
