I've read here that a suspension period can last at most one year. But I found an account which is obviously suspended for $\textbf{10 years}$ :
Have the rules been changed or has an error crept into the system?
I've read here that a suspension period can last at most one year. But I found an account which is obviously suspended for $\textbf{10 years}$ :
Have the rules been changed or has an error crept into the system?
The limit of a one year suspension that you referenced is for that by diamond moderators on any one site. However, only Stack Exchange employees may issue network wide suspensions for longer than a year, as the network Meta FAQ My account has been temporarily suspended; what does that mean? post's answer states:
What is a network-wide suspension?
A network-wide suspension is applied to all network accounts of a user. It can only be issued by Stack Exchange employees and can be longer than 365 days. The most common reasons for a network-wide suspension are spamming, trolling, and to cool down.