¿Por qué no es la lectura de los parámetros?

La ruta de los componentes debe ser pasado como JSX, no como una función invocada.

<Router>
  <Routes>
    <Route path="/" element={<p>Homepage</p>} />
    <Route path="/join" element={<JoinRoomPage />} />
    <Route path="/create" element={<CreateRoomPage />} />
    <Route path="/room/:roomCode" element={<Room />} />
  </Routes>
</Router>

Router

<Router>
  <Routes>
    <Route path="/" element={<p>Homepage</p>} />
    <Route path="/join" element={JoinRoomPage()} />
    <Route path="/create" element={CreateRoomPage()} />
    This is the roomCode i want to read in the Room Component
    <Route path="/room/:roomCode" element={<Room />} />
  </Routes>
</Router>

Sala De Componente

import { useState, useEffect } from "react";
import { useParams } from "react-router-dom";

const Room = (props) => {
    let { roomCode } = useParams();
    const [room, setRoom] = useState({
        votesToSkip: 2,
        guestCanPause: true,
        isHost: false,
    });

    return (

        <div>
            <h3>{roomCode}</h3>
            <p>Votes: {room.votesToSkip}</p>
            <p>Guest Can Pause: {room.guestCanPause}</p>
            <p>Host: {room.isHost}</p>
        </div>
    );
}

export default Room;