The documentation Configuring an announcement banner states that the permission for configuring the Jira announcement banner is Jira Administrators when, in fact, the required one is Jira System Administrators.

Amplifying the reach of this FR, there are many documents that should get updated.

By default, Jira does not create a Jira-System-Administrator group, just the Jira-Administrator one with total access. Then the admins tend to segment the administration roles to have different levels for safety and best practices. So if Jira Admins creates two different admin groups and give them different access levels, perhaps Jira-Administrators and Jira-Sys-Administrators, each of them holding a different Jira permission level, then there will be a few differences in what each of the permission allows the admins to do, but the documentation is not clear enough about that.
e.g. The only one that presents the Announcement banner matter is the Jira 8.13 Managing Global Permissions article.