You are using a PCI 4.0 SSD compared to the SSD used in this RAIDZ2 with PCIE 3.0
10 PCIe 4.0 SSDs give you maximum of around 70GB/s.
The test show sustained throughput of 80GB/s without compression. Which is still higher than the maximum allowed by 8 x 4 PCIE 3.0 slot at total of 32GB/s.
Waiting for some ZFS expert to give a plausible explanation.
https://news.ycombinator.com/item?id=25956670
Had to use direct I/O and use random large IO patterns to avoid various caching, buffering and prefetching effects.