This document explains certain behaviour based on certain scenarios
The BulkOps app for Jira (Pro) automatically identifies a user and creates them based on their instances. If in a scenario, your instance URL is renamed, this will affect your user profile as the app will determine it as a new user due to this change. When a rename is done, an update should be triggered on your app automatically which should take note of the change in URL in your Jira environment. If this does not happen and causes any issue with app accessibility, the best option would be to uninstall and reinstall the application again.
If you need this user to be synced as the same, please raise a support request so we can correct this changes by replacing the new user with the old user.