What mods does the hermitcraft server use?
As of Hermitcraft Season 8 the Hermitcraft server uses two fabric mods Lithium and Simple Voice chat.
Lithium
Lithium is a server side performance mod for fabric, it gives around a 45% performance boost without changing any vanilla mechanics of the game. It optimizes Physics, Mob AI, World Generation, Chunk loading, Mob Cramming, Block Ticking, Explosions, and Data Tracking. This is what allowed Xisumavoid to raise Hermicraft's View Distance in Season 7 to 16.
Simple Voice Chat
Simple Voice Chat is what the Hermitcraft server uses for proximity chat. This mod is how they communicate to each other in game in a proximity based fashion, meaning they have to get up close to each other to talk. If they're farther away they're quieter or they can't be heard at all. This is a lot more engaging way of interacting with each than just using Discord.