Hi all,
In Jira cloud, sub-tasks cannot be created under the issues at the level of Epics and above. They are always can be added under the issues which are at the level Story, Task, Bugs etc.
However, I have observed in Jira data center, you can create sub-tasks under the Epics as well. Even if you create an issue type above the 'Epic' level (via Jira Plans/Advanced roadmaps), those higher level issue types also allow creation of sub-tasks under them.
I want to know if this is a bug or it is by design. If by design, what is the utility of this? How often teams use this structure and is there a way to disable it.

Thanks in advance.
Regards,
Sujeet