All Kubernetes workload types (REPLICASET, STATEFULSET, JOB, DEPLOYMENT etc) can show as "No recommended change".
Workload types will show "No recommended change" when they are short lived and not picked up by our collector (which collects every 15 minutes).
Also, any REPLICASET that is managed under a DEPLOYMENT will always show as "No recommended change" since it's already factored in to the DEPLOYMENT rightsizing recommendation. However, a standalone REPLICATSET can be rightsized.