Applying QoS limit of 500 IOPS to a Volume consuming ~200 IOPS and latency goes crazy

[Nexica]

Why when we apply a QoS Policy of 500 IOPS to a Volume consuming ~200 IOPS the latency goes up?

The QoS policy is not shared among other volumes, 1 QoS policy -> 1 volume. We are running ONTAP 8.3.1

Note: image from grafana & netapp harvest