xja wrote:The grain surrounding the serial number is because of jpeg compression.
Learn about it here
Oops, seems that you are right and VH is indeed a new letter combination on the serial number.
H and Z share the same checksum value (zero). I wonder if this means that VH is some kind of test serial put in circulation, just like we suspect to be the case for NZ and XZ. (SZ has also been printed but keeps on not showing up in the wild.)