I would expect user and group change notifications to be issued when corresponding custom security attributes are updated, but that doesn't seem to be the case. How can we be notified when changes to custom security attributes occur?
PM for Graph Change Notifications here.
We do not currently offer the ability to provide change notifications for custom security attributes.
This is a common ask and we have a work item on our backlog to figure out how to provide these. Any change here though would likely be at least a year out.