Copy-pasting my other comment:

Raddle is the main instance of Postmill, Postmill is the software behind raddle. Its kinda like calling Lemmy hexbear. Also:

Yes, I messed it up, I’m sorry. It’s because this time, when I started writing the code, I used my old repositories and snippets (back then, I was heavily inspired by Postmill). I wasn’t sure if the project would even leave my drawer, so I didn’t focus on it, I was just prototyping. I had plans to organize everything before the release of the first alpha version. This is my first major open-source project, and I haven’t developed good habits yet. So I have no excuse for myself. All I can do is apologize to Emma and all the PM contributors. I will fix it as a priority. 👍 - Ernest (kbin dev)

[…] I’m fine with you using them under attribution. - LitigiousEmma (postmill dev)

See https://codeberg.org/Kbin/kbin-core/issues/196

Also: Postmill is licensed under Zlib license not GPL. Even if, this would violate GPLs terms, as Ernest did not attribute the code to Emma.

TL;DR: Some of the of the kbin source code was copied from/based on postmill, but its an issue of attribution. Some of kbins source code is original, as kbin has features (most notably federation) that postmill does not. This issue also only applies to kbins backend.