Quick leave

Quick Leave is a lightweight client-side utility mod that adds an instant disconnect keybind for Minecraft 1.21.
Features

Instant Disconnect — Press your keybind to instantly leave any server without touching your mouse
Double-Tap Safety — Tap once to arm it, tap again quickly to disconnect. Prevents accidental rage quits
Configurable Timing — Adjust the double-tap window anywhere from 100ms to 1000ms in the settings
Always Sprint — Automatically sprints whenever you move, persists even after rejoining servers
Clean UI — Full settings screen accessible through Mod Menu

Requirements

Fabric Loader
Fabric API
Mod Menu

How to use

Launch Minecraft with Fabric
Go to Options → Controls and find Quick Leave to set your keybind
Go to Mods → Quick Leave to configure settings
Press your keybind twice quickly on any server to instantly disconnect