There are many. I should really document my findings in some sort of analysis. I've pointed this out to some friends who have payed closer attention and now agree with me after observing it for the last year or so themselves and comparing articles on the same topic between the WaPo and other sources.
I personally am strongly anti-Trump but also broadly dislike both major parties, so citing a WaPo article that is unfair to Trump sounds to many people like I must be a rabid Trump supporter. But in reality I'm just someone who wants journalism to be journalism and focus on facts and strives to do analysis that would be respected by people on all sides of an issue politically.
The decline in quality and shift to partisan and sloppy reporting is the most dire consequence of the Trump era. It's impacted the big newspapers the most. I think part of it is that they feel responsible for getting him elected, but part of it is that their new way of thinking about their KPIs rewards them for writing anti-Trump clickbait.
So they are at once reinforcing Trump's ability to control the news cycle and make whatever story he wants front page news, while writing coverage in a way that loses the trust and respect of anyone whose goal of reading news is non-partisan or even partisan from the other major party perspective. Sadly this allows Trump and orgs like Fox to be viewed by some as the only form of true news. It's really horrible.
No political party or news org benefits from any common ground or shared truth, they all benefit from loyal fans who pay them a monthly subscription fee for content that is mostly entertainment. This is the Fox News model, but it's now been adopted by the WaPo and NYT in their own way. They still do produce some very solid journalism, but it took the NYT several years to write the story on Trump's inherited wealth (which was excellent) while in the meantime it published a LOT of garbage stories every day that fanned the partisan flames and generated revenue while providing zero journalistic value.