Related note:
I got a simmilar experience.
Ill make a induvidual ticket to find out why my updates fail this way.
I updated unraid 6.9.2 to 6.11.5 and got the same error.
The server did not start after the update and gave me a superblock error.
I couldnt get into the server remotely anymore.
The device that gave me the error unraid /dev/loop0 /boot/bzmodules error
I had to remove the USB from the server and opened it on a laptop.
The loop0 seemed to be the bzmodules.
So I copied the content of my flash-drives previous folder over the files on the USB.
Put the USB in the server, started.
At boot the server download/written a file or 2.
And then the server started as before.
This fixed the error for me.
Still cant update to 6.11.5 succesfully