Back then, I did a digital marketing related to crypto and they were also using Discord server for the engagement. It is the first time I hear about Discord being used for anything crypto-related since Discord is widely used mostly for gaming stuffs.
Though I would say Telegram is far more used still as from my observations as I did track someone's crypto wallet daily transaction and they were all still using Telegram instead of Discord.
Either way, it does not matter anyway since both of these are free to install regardless.