This server is called CheesyCraft Redux and it is a semi vanilla survival world. It runs on version 1.21.11 so it is pretty up to date.
The owner and staff make their own custom features just for this server. The code is done by the team and a lot of the textures are made by the community so it still feels like normal Minecraft but with a unique look.
They keep everything simple and focus on quality over quantity. There are some quality of life commands and features but they do not spam you with random crates or resold cosmetics or tons of confusing systems.
They use plugins like GriefPrevention so your builds are safe and CoreProtect to watch for problems. There is also Simple Voice Chat and a map plugin called squaremap.
The staff and builders are people like GentlemanCheesy and Power and a few others who help build and program. The server wants players who enjoy survival and want to try out their custom stuff in a relaxed way.
