I'm a bit confused about where threads are coming from, it's hard to see if it's local or federated.

Take this post, for instance:

https://fedia.io/m/[email protected]/t/6403/Does-lemmy-world-allow-criticism-of-the-CCP

The user and magazine are both from Lemmy.world, but next to the title it says (fedia.io). What does that site in the parentheses mean?