https://www.wired.com/story/twitter-fact-checked-trump-tweets-mail-in-ballots/

On Tuesday, in this most normal year of 2020, President Donald Trump woke up, hopped on Twitter, and fired off a few tweets amplifying a conspiracy theory that a cable TV host he dislikes had murdered someone decades ago. Later that day, for the first time, Twitter made the momentous decision to flag Trump for tweeting false information. Amazingly, it was in response to a completely different set of tweets.

It was a bold move, long awaited by Trump’s critics, and Twitter’s. It was also a clumsy one. With less than six months until what could be the most contentious American election since the Civil War, social media platforms have clearly still not cracked the code of political fact-checking.