internal comments getting automatically sent out as reply to customer

[Tshering Wangmo]

We are facing this weird issue of the internal comments being sent out as Reply to customer. 

[Ollie Guan]

Hi @Tshering Wangmo ,

In a JSM Cloud Premium environment, internal comments leaking to customers is typically caused by Notification Engine Overlap or Over-permissive Access.

The culprit is usually the Jira System Notification Scheme. Unlike JSM Customer Notifications, the system scheme does not respect the "Internal" flag.
Quick Fix: Go to Project settings → Notifications and check if Reporter or Watchers are listed under the Issue Commented event.

[Charlie Misonne]

If the suggestion from @Ollie Guan does not solve anything I'd look into any automation rules sending notifications.

You can open a work item for which a notification was sent and look at the automation runs for that specific item.