So I looked into this and it is growing due to search traffic and auto translations in international markets. In US the main audience is young adult men 18-28 (makes sense). Low women users, low teen. Teens prefer short video format. X is mostly an adult platform, teens leaving. Facebook is for grandma.

What is not known is how much of Reddit growth has anything to do with popularity of communities vs simply pushing users into the app and accessing wider markets through translations.