No externally validated test reports have been published in past years (2016-2020).

However, in May 2019 StorPool did publish an internally validated performance benchmark test:

Intel Data Center Builders (Jun 2019)
Title: "The IOPS challenge is over. StorPool holds the new world record – 13.8 mln IOPS"
Workloads:
Benchmark Tool: FIO
Hardware: All-Flash x86-based servers, 12-node cluster, 25Gb Ethernet connected, SP v19, 4x Intel SSD DC P4510 8TB NVMe per node

For more information please go to:
https://storpool.com/blog/the-iops-challenge-is-over-storpool-holds-the-new-world-record-13-8-mln-iops
or
https://builders.intel.com/blog/the-iops-challenge-is-over-new-world-record-is-hit-13-8-million-iops/