I'm trying to join the discord server with the link you posted on the main jam page, but it just says that the invite is invalid. It worked before, so I guess the link expired? Or is this something on my end?

Sorry about that!  It appears the Discord links do expire after a certain amount of time.  Here's the new link: https://discord.gg/zTvaKNhS

Thanks for pointing it out!  I'll update the jam pages.