Is it possible to restrict auto delegation population to only HRs and Managers? Currently all active users appear in the drop down.
Employee Central: Workflows
This is an expected behavior.
By design, we don't apply target population restriction for manual delegation, auto delegation and auto escalation. It is up to user to decide who will help them finish the approval task.
You can raise an enhancement request in Customer Community. Refer to the KBA 2090228 - How to submit enhancement requests for SAP SuccessFactors products to know how to submit enhancement requests.
confine, target, ECT-58784 , KBA , LOD-SF-EC-WFL , Workflow & Trigger (Rules & XML) , Product Enhancement