Restricting create access by Issue Type

We need the Dev Team to manage their sub-tasks but not be able create Stories. Not being able to restrict that means that either the Product Owner has to create ALL sub-tasks on behalf of the team or the PO has to constantly keep an eye out to make sure no one else creates Stories because giving access to create sub-tasks also gives access to create Stories. This is a very combative situation for the team and PO. Please prioritize this for sooner than later as it's obvious this is needed because "Automation for Jira Lite" Add-on is being used to fix this after the creation by a lot of Jira users.