Labeling activities are available in Activity explorer.
For example:
Sensitivity label applied
This event is generated each time an unlabeled document is labeled or an email is sent with a sensitivity label.
It is captured at the time of save in Office native applications and web applications.
It is captured at the time of occurrence in Azure Information protection add-ins.
Upgrade and downgrade labels actions can also be monitored via the Label event type field and filter.