This site uses the youth protection label from JUSPROG.

“There is a technical standard in Germany and Europe for a youth protection label for age classification of websites. The age.xml /age-de.xml label is officially established in Germany by the criteria for youth protection programs of the Commission for the Protection of Minors in the Media (KJM). It makes sense to integrate the label, JusProg has already integrated the age.xml and age-de.xml label into its filter software.

Very many large and small website operators have already installed an age-de.xml label, including almost all private TV providers from RTL to Pro7 and Sky, many gaming portals, Youtube, bild.de, spiegel.tv, to name just a few of many examples, and also almost all state media authorities as well as various other state websites and all self-regulatory bodies.

In Germany, the age-de.xml label is mandatory for website providers who want to protect minors from the content of their website according to § 11 JMStV. Internationally, the age.xml file applies.”

For more info https://age-label.com/parents/ 
For Germany more info at https://jugendschutzprogramm.de/