The media's biases are driven by their audience and what their audience wants is drama. In an election year, this means they need A) new and fresh storylines and B) a close election. So newsrooms will be digging frantically for something in Biden's past and they'll no doubt find it (if politicians were good people, they wouldn't be in politics). The conservative outlets will pick it up first (maybe Fox News or The Daily Caller) and other outlets like CNN will have to jump on it or risk losing audience. As a result ...
Trump Will Stage A Big Comeback In The Polls
Right now (late June) all of the polls average out to about a 10-point lead for Biden. For context, at this point in 2016, Hillary was up by about six. As for whether Trump can come back by November, well, on one hand, you could point out that he never made up the difference in 2016 -- the final polls still had Hillary up by four and then it turned out they were off by two (Hillary won the popular vote 48% to 46%). But on the other hand, Trump is now the goddamned president.
The electoral college, a system set up so that empty pieces of land get to cast votes, is arranged so that Trump could lose this election by around five points and still get a second term, thanks to the corn fields that love him. So when I talk about Trump making a comeback in the polls, keep in mind that he doesn't have to gain back all ten points (which would require something like Biden admitting he accidentally created COVID-19 while operating a bat-fighting ring in his garage). If Trump can get it back to where he's down, let's say, 48-44, I'd absolutely expect him to win in November.