Limit Whom to Reassign or Delegate Workflow Tasks To
Limit Approval delegation is limited based on the Public Person Security Profile
Starting from 21, Oracle introduced this feature that should allow to limit the workers to whom delegate a task from Me -> Roles and Delegation - My Account.
The issue is that the limitation is done based on the Public Person Security profile. So basically if the employee already has a role with a public person security profile attached, this can't be limited unless we change the public Person Security profile on the already assigned role. But changing this will have impacts on directory search and other feature.