It was announced as a FSK 18 DVD but then released as a FSK 16 after a new certifying through the FSK
But it seems between announcing it and releasing it Koch changed it's policy towards releasing FSK 18 DVDs. Shortly before the release it was newly certified and got now a FSK 16 rating. The released DVDs are all with the FSK 16 logo.
Since then all Koch SWs of FSK 18 films were newly certified (for which they have to pay) and normally they all get the 16 rating. Koch didn't spent the money for the older titles, but most likely the sales weren't as good as for the lower rated SWs and now they pay the costs. That's why the Ringo films are still FSK 18, but the much more violent Dead Men Ride now FSK 16.