Luckily there’s a preprint of the article on arXiv if you want to read the source material for the article.
My basic summary would be that they have a model for how variable a quasar should be over time, and they can see a difference in that variability depending on the quasar’s redshift, the distance from us. And that difference is right around what we expect from relativity.
Yup! The GMs are a lot more active recently, adding things to the game continuously. And now there's regular scheduled events where the GMs push stories and interaction to a level we haven't seen in a decade.