I struggle with this too. While I'm currently in a rut myself, I always try and tell myself that if I just make something with passion for me, then other people will catch those vibes and hopefully love it too :)

Hey there! I havent joined too many myself, but I find the best way to find jams to join is by looking on itch.io/jams! Every jam is different, some are restricted to certain engines or themes, and you can usually work solo or with others! Take a look around and try to find something you like 😊👍