The way it works is that:

• If you do not enter any emails in Super User Emails parameter of the plugin, all Super Users will receive update notification
• If you enter some emails into Super User Emails parameter of the plugin, only Super Users who has these emails will receive notification (basically, some kind of Super Users filter)

Not sure if that's the information you are looking for?

Thats how I thought it works which means that the code comment "or a predefined email address" is confusing because that predefined email address must also be that of a Super User.

See #33766