I don’t have anything against IRC, but to suggest it as an alternative to Discord shows such a fundamental lack of understanding of what Discord is good for that I’m kind of baffled. If you’re looking for self hosted alternatives then Matrix (especially with the latest video/voice chat rooms)is much closer to what Discord offers, but even that isn’t really a viable replacement for the core use case of Discord: voice chat while gaming + seamless video streaming of captured game footage with a UI so smooth that my 8 year old nephews figured it out on their own.