No, they haven't. News organizations have always had strong political and narrative-driven tendencies, what has changed is that the media is more diverse in bias and thus the illusion of neutrality that came from the period where the major national media spoke with nearly uniform bias and agenda is lost.
When other outlets shill for the RNC, that isn't the same as having "political tendencies."
In the past, these maneuvers would have been considered conflicts of interest and a violation journalistic ethics. Today, we don't have many practicing journalists. We have "here's a lefty and here's a righty, let's watch 'em argue on screen" passed off as news.
The thing about "what has happened" is that it actually leaves a lot of room for bad faith reporting. You can never include everything. What isn't reported is just as important as what is, whether it's whole stories, certain viewpoints, context, anything.
What criticisms did mainstream news outlets level at George W. Bush that you felt were attacks? At what point in the lead-up to lies-based invasion do you feel it's ok to say "Bush and Cheney just might be lying here, folks."?
The moment Obama was elected those counts stopped.
We all want to believe that nice guy on TV. Is honest and neutral.
This is almost never the case.
Notice how in the first few months of the pandemic the daily stats were front page? Like, every day and multiple times per day. Now we just occasionally get the "USA breaks single day record" second or third level heading with no specific numbers.
But, I promise you in 4 years people will be remember this as "Remember when the media was reporting the pandemic deaths non-stop when Trump was in office but it _suddenly_ stopped when Biden was in office?"
Just like people seem to remember when "Mitch Mcconnell" overrode Obama's veto. The veto both houses and both parties overrode. 97-1 in the senate.
Couple that with people remembering things how they want, or believing what they want to hear, and Bob is you uncle.