I think one reason is the large number of German users on the Internet. With around 100 million speakers, German is the second most spoken native language in the West after English.
According to the application texts, many users seem to come from various podcasts. We are also “endorsed” by one of the largest German-language subreddits on its front page (r/ich_iel). Our users have also started to watermark their memes, which occasionally attracts new users. Feddit also made it into an article in a popular IT magazine (heise).