alt Hacker NewsWho is they? Which services?
From what I can tell, the article/paper in question does not appear to utilize any of the techniques you mention, but I'd be interested to learn more about it.
> it's the nuances behind the way you type
I found this paper which talks about some of those methods.
https://www.audiolabs-erlangen.de/content/04_fraunhofer/assi...
For example the "Text" section on page 91.
The big companies that sell prediction products to advertisers. Google, Amazon, Microsoft, Apple, Meta... all of them are involved. I didn't read the paper but this is a known method they have been using for awhile to track people across sites of many types from social networking to online shopping sites