Why do I see JIRAUSERxxxx as worklog author

This article is for Tempo for Data Center.

Question

Why do I see JIRAUSERxxxx as worklog author?

Answer

Due to GDPR change, Atlassian has changed the way to identify a user. This change was introduced in Jira 8.2 and new users that are being created in Jira get a userkey in format: JIRAUSERXXXX. This userkey is the unique identifier of a user.
Tempo uses this information to look for user information linked to a worklog.
You can read more about this userkey change in the Atlassian documentation, more specifically, in this article.