A hostname that is found in source code is neither suspicious nor malicious on its own. The hostname itself and the context in which it occurs determines that.
Hostnames appearing in source code should be carefully scrutinized to insure that a nefarious actor is not reaching out to a network resource that could deliver harmful material.
Hostnames may have legitimate uses, but they can also be used in malware.
mathjax.org hostname in the package contents.
On the other hand, a ransomware attack in 2020 used a hardcoded hostname for the target.
Hostnames that do not have a clear and obvious connection to a package's functionality should be treated with suspicion until their legitimacy can be established.
Updated 5 months ago