Newspapers are all part of the same business group and operate through "carpetbagging" - promoting whatever it takes to get sales and clicks and keep a position of power.
It's naive to think they have the Guardian has some idealistic attachment to justice or supporting or believe in any point of view, they just what they can do to get sales and promote their own importance.
They make money through the same stories, "playing both sides of the equation".
It's not like the noble leftie journalists are speaking against the nasty tabloids or vice versa - they all are profiting from the set-up. It's the people who trust them or the people who they report on who are normally the victims or caught in the crossfire.
Journalists will move between different papers, they don't believe a word of what they write unless it makes sales or conforms to a particular agenda or targets a particular person the paper's Editor wants targeted!
The editor of the Mail was known to be close friends with the editor of the Guardian .The Guardian wrote a massive sycophantic "flattery piece" about Paul Dacre's son when he took on a new job.
With the trans movement, there's been a clear attempt by organisations like the BBC and the Guardian early on to "set up" vulnerable young people and "promote their surgery"
And then they know a few months later, afterwards the Mail gets to run articles humiliating the same young people with "sadface" articles. The culture is of drama and clickbait and "making stories".
JK Rowling has never been well supported by any sections of the Press. Even the BBC runs vicious articles on her!
She was a woman who got so commercially successful early on and was an "early adopter of Twitter and her own blog" so she didn't need to use the media for tacky promotion, and received extreme harassment from a lot of the Press (including the broadsheets and of course the Mail etc) and testified against them in the Leveson Inquiry.
Plus, beautiful, successful, philanthropist, married a doctor - the jealous media knives were out for her early on!