There is no conspiracy and there is no coordinated media effort to harm DC movies.
The press likes having something juicy to write about. It's that simple. The movie isn't great and it's underperforming at the box office. That is a story, and in order to get clicks, the media is going to play those things up.
Conspiracy or not.. DC gets a tougher ride than marvel...bar SS all their moveis are solids however they all get battered.... Marvel's turds even get 4 star reviews.