plane/apps/app/components/rich-text-editor/toolbar/undo.tsx

import { useCommands } from "@remirror/react";

// icons

export const UndoButton = () => {
  const { undo } = useCommands();

  return (
    <button
      type="button"
      onClick={() => {
        undo();
      }}
      className="rounded p-1 hover:bg-gray-100"
    >
      <svg xmlns="http://www.w3.org/2000/svg" height="18" width="18" viewBox="0 0 48 48">
        <path d="M14 38v-3h14.45q3.5 0 6.025-2.325Q37 30.35 37 26.9t-2.525-5.775Q31.95 18.8 28.45 18.8H13.7l5.7 5.7-2.1 2.1L8 17.3 17.3 8l2.1 2.1-5.7 5.7h14.7q4.75 0 8.175 3.2Q40 22.2 40 26.9t-3.425 7.9Q33.15 38 28.4 38Z" />
      </svg>
    </button>
  );
};