We ask to run memtest when checksum errors are detected, that's not your issue, your problem is that one of the NVMe devices dropped offline:
Aug 10 21:44:19 Vortex kernel: nvme nvme1: I/O 130 QID 1 timeout, aborting
Aug 10 21:44:19 Vortex kernel: nvme nvme1: Abort status: 0x0
Aug 10 21:44:26 Vortex kernel: nvme nvme1: I/O 183 QID 1 timeout, reset controller
Aug 10 21:45:33 Vortex kernel: nvme nvme1: I/O 15 QID 0 timeout, reset controller
Aug 10 21:46:27 Vortex kernel: nvme nvme1: Device not ready; aborting reset, CSTS=0x1
Reboot/power cycle to see if it comes back online and run a scrub, also see here for better pool monitoring.