The media are on the hunt for a bad story they can hang around President Trump’s neck. Why? Because President Trump’s approval rating continues to hover around 50%, which is a historic high for him.
The SignalGate story basically went nowhere because the truth is that everybody has, at one point or another, included somebody in a group chat by accident and it gets very awkward. The actual result of the Signal chat was kind of an embarrassing snafu. The military strikes on the Houthis, however, were totally successful. The United States military is currently eviscerating the Houthis in Yemen.
So the media continue on the hunt.
There are certain stories that are so bad for an administration that they end up hampering their ability to do anything because association with the administration becomes toxic. And there have been many cases of this over the course of modern American history.