The question of how Tucker Carlson's head writer got busted for his racist posts is actually pretty interesting and mysterious: https://www.cnn.com/2020/07/10/media/tucker-carlson-writer-blake-neff/index.html

Based on the info in this article, we can see that Neff used the username "sickened dilemma" on the troll forum AutoAdmit (xoxohth) to make the posts. But...

... As far as I can tell (AutoAdmit makes itself intentionally hard to search), there's no link between "sickened dilemma" and Blake's name. And there's no records of that username on other websites linked to a Blake.

It's*possible* he left a trail of crumbs and someone who followed his writing on AutoAdmit closely figured it out.. but that's a leap.

My current guess? iffy, but maybe someone in Fox News' IT dep't leaking to the press. Never piss off the guys who can see your browsing history.