That is only relevant for instances hosted in Germany, and also why feddit.de and discuss.tchncs.de (like most instances, though) defederated from NSFW instances.
Age gates are a joke and almost no one uses them, xhamster even flouts the law and changes the German subdomain whenever there is a new idiotic ISP DNS block.
Related anecdote: I was hosting an erotica forum (which I started doing when I was 14 or 15 …) when the law came to be, we had to get a Jugendschutzbeauftragter (youth protection officer; luckily something that existed “as a service” for like 5€/month) and implement an age gate. This killed the site.