Not doing any code reviews? Leaving tests "for somebody else to write"? Refusing to work on legacy code-bases and only working on greenfield projects? Tuning out (or just not even joining) API design meetings so you can work on your own stuff? Bonus points if you have the authority to turn around in a few weeks and make folks re-write the API because you don't like the decisions you ignored - those pesky 1x engineers, eh?
There's a bunch of things that fit into this category that can make an engineer seem like they're doing 10x the work, but if you look closer it's frequently only because they're taking shortcuts or pushing more work onto their colleagues.
To be clear - I'm not saying 10x engineers don't exist, just that folks with "teamwork issues" who appear to output 10x as many features are frequently not as productive as they seem.