I was only flipping between file systems to force it to reformat the drive with hopes the message would go away.
If I look in dmesg, I see the following ONLY for disk8. I want to understand why this is only for md8 and none of the others. It looks like an ominous warning even though everything appears to function fine.
root@Deathstar:~# dmesg | grep md8
[ 116.577230] md8: running, size: 13672382412 blocks
[ 118.259234] md8: stopping
[ 225.828873] md8: running, size: 13672382412 blocks
[ 229.265795] XFS (md8): Invalid superblock magic number
[ 277.632501] XFS (md8): Mounting V5 Filesystem
[ 277.790518] XFS (md8): Ending clean mount
[ 277.795654] XFS (md8): EXPERIMENTAL online shrink feature in use. Use at your own risk!
deathstar-diagnostics-20220208-1633.zip