The change of issue type is considered a "move" event, but it could cause misunderstanding as the issue will be "edited" when the issue type is changed.

In order to prevent this from happening, you may use the workflow property "jira.permission.move.denied". However, please note this will also prevent the issue from being moved to another project.

We could improve this by allowing a "Move" to happen, but only to a different project and not to a different issue type in the same project.