Except the reason for Discords initial success, and the literal only reason I have it installed, is for voice chat when playing certain online games.
I love IRC, I even wrote my own IRC client in the 90s, but it’s clearly not going to be suitable for gaming in this context.
IRC for main chat, Mumble for voice chat when gaming. Been solid for decades. I have at least 3 functional Mumble servers saved (including my own) in my client, most of them are associated with an IRC community. I occasionally hear "Anyone down for some Quake? Hop on Mumble." or something to that effect. Mumble is pretty easy to host, so if you're using it with a small to medium group of friends, I'd say just throw up a server on your LAN somewhere. It's got decent mobile clients on F-Droid as well if you need one.