Hi,
DC, It is not a plate flaw but an interesting stamp. Like Peter wrote, the after war production was not as good as before.
That brought a lot of quality issues.
The 80 Pfg of bookbndrbob is a good example as well.
Quality issue in the printing and perforation. Using worn perforation machines made such nice varieties. they are known and catalogued.
Hornet
Here some examples:
Metal in gum:

Perf variety:

Plate flaw on Nr.922 (Position 80 on HAN 4042.46 1)
