When I was a kid, "Breaking News" was only used for urgent announcements that had to interrupt something else. If the story about the kid who did the nice thing had to be cut short because there was another school shooting, that was breaking news.
That seems like it was such a long time ago. Now it's pretty much just the TV equivalent of clickbait, it doesn't mean anything anymore. They just put it in front of all the top stories indiscriminately.
When did it change?
How do you know it did change? Maybe the media manipulation started before then and what you consider the true stories were actually propaganda? Maybe it's only coming out now because they had a slip in people pointing out the propaganda. Maybe you're seeing the same manipulation now that you saw 15 years ago