This takes a degree of understanding of what you are doing and why it fails.
I've done some research on this myself and the answer is the USB controller. Specifically the way the USB controller "shares" bandwidth. It is not the way a sata controller or a pci lane deals with this.
ZFS expects direct control of the disk to operate correctly and anything that gets in between the file system and the disk is a problem.
I the case of USB let's say you have two USB - nvme adapters plugged in to the same system in a basic zfs mirror. ZFS will expect to mirror operations between these devices but will be interrupted by the USB controller constantly sharing bandwidth between these two devices.
A better but still bad solution would be something like a USB to SATA enclosure. In this situation if you installed a couple disks in a mirror on the enclosure... They would be using a single USB port and the controller would at least keep the data on one lane instead of constantly switching.
Regardless if you want to dive deeper you will need to do reading on USB controllers and bandwidth sharing.
If you want a stable system give zfs direct access to your disks and accept it will damage zfs operations over time if you do not.