Hi Matthew,
welcome back. Redmine as a self hosted software for project management had a hard time competing to all those shiny SaaS platforms which became popular in the last decade. I think it has lost its momentum in this time. Most of the dwarfs form the early days have left the project and JPL has not much time for it either. There's not much we can change on redmine.org without him. So redmine.org has not changed very much since I was introduced to Redmine about ten years ago. But to the day it's a reliable solution with a hand full of dedicated developers and it's used by many people.
There was a Discord server some time ago which was quite popular in the beginning but it was shut down by its owner quite suddenly. At the moment there's a Slack workspace which was created by some core developers.
Things are getting better but it needs time and dedicated people to bring Redmine to its second spring.