Jia Tan was the username used by a group

probably a state intelligence agency

on GitHub to try to attack the xz open source package. The effort aimed at trying to take over the project, and lasted for years. They managed to get a compromised package briefly into the unstable versions of some major Linux distros that created a backdoor in the openssh daemon and came close to being widely deployed across Linux servers, which would have been a very severe compromise of a huge range of systems. The account vanished when the compromise was discovered.

The user here is, as a joke, using the same name.

EDIT:

https://en.wikipedia.org/wiki/XZ_Utils_backdoor