Update: SOLVED

I installed a temporal server, and copied all vms (it took a few tries, but eventually finished ok)

With the main server out of production, I took it to my office, and found out that the memory was making some errors. Only 3 or 4 errors with each Memtest Pass.

Replaced memory, and 1 NVME SSD that died, clean 8.2.1 install, and its working OK with no errors during backup

Thanks!!!!