I have 2x servers each with 8x 3.84TB Enterprise SSDs in raidz2, with ashift set to 13.
Proxmox version is 6.4-13. (I'm doing an update as I write this post)
They are configured in a two node cluster (I haven't got a third node, yet!)
On the node status pages,
Box #1 reports 18.03TiB usable...