Servers tagged Version1.8 usually run on Minecraft 1.8.x (or emulate its mechanics) to keep the pre-1.9 combat style with fast clicking, no attack cooldown, and the old movement/hit registration people associate with classic PvP. It’s common for practice, kit PvP, factions, and minigame networks that want the 1.8 feel, sometimes allowing newer clients via ViaVersion while still using 1.8 gameplay.