godot/scene/theme/icons/folder_up.svg

<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16"><path fill="none" stroke="#b2b2b2" stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M8 11V4m4 4L8 4 4 8"/></svg>