Keys of non-estimated sub-tasks
Return the keys of the sub-tasks that do not have original estimate or story points estimate.
Configuration
Create a Custom smart text field and use the Jira expression parsing mode.
Expression
CODE
issue.subtasks.filter(s => s?.originalEstimate == null && s?.customfield_nnnnn == null)
.map(i => i.key).join(", ") 
Please, note that it is necessary to replace nnnnn with the ID of the custom field displaying the original estimate or story points.