A Deep Clone for Jira installation requires the following scopes:
“Read” is required to get information about the original issues, e.g. project configuration. Deep Clone uses that information to prepare the clone dialog and prevent errors.
“Write” enables Deep Clone to create the cloned issues in your instance.
“Delete” is needed to remove field content which is not desired, e.g. when you don’t want to clone watchers.
Deep Clone also uses “delete” to prevent unnecessary notifications when comments are cloned. When a comment is cloned, Jira adds the commenter as a watcher. Deep Clone immediately removes the watcher to prevent that a notification is sent.
“Admin” is required to get information about workflows. It also enables Deep Clone to clone issues that cannot be edited by a normal Jira user (e.g. closed issues).
“Act as user” is required to clone comments and worklogs, making them appear as if they were added by their original author .
You can read more about scopes in the Atlassian Developer documentation.