For questions about network-wide suspensions, which can be applied by the SE team and prevent users from contributing across all SE sites.
For questions about network-wide suspensions, which can only be applied by Stack Exchange employees and prevent users from contributing across all Stack Exchange sites. Unlike moderator suspensions on a single site, which are capped at one year, network-wide suspensions can last for a very long time.
It's rare, but an account can be suspended for a protracted amount of time when all other attempts at reasoning have failed when it comes to a certain type of behavior.
If you see that an account is suspended network wide for more than a year, it's a strategic move on the part of an employee with developer access to bring something disruptive under control.