I tried creating a new API token and pasted it in a .env file and updated the jsx file imports,

const Dashboard = () => {
    const navigate = useNavigate();
    const [user, setUser] = useState(null);
    const [loading, setLoading] = useState(true);
    const [viewport, setViewport] = useState({
      latitude: 6.9318,
      longitude: 79.8863,
      zoom: 10,
    });

  <ReactMapGL
            {...viewport}
            mapStyle="mapbox://styles/mapbox/streets-v11"
            onViewportChange={setViewport}
            width="100%"
            height="100%"
            mapboxApiAccessToken={import.meta.env.VITE_MAPBOX_ACCESS_TOKEN}
         />
}