Im aware. Its not due to the age rating but due to there being a tit in it at some point
Sorry for the late reply.
In Germany the game either needs an age rating via the USK (PEGI is not valid in Germany) or an age rating that is issued by Valve through its own self-rating process.
The self rating process should be available for you under the following link: https://partner.steamgames.com/healthcheck/missingratingforgermany/