I'm new in ReactJS and JavaScript and I'm trying to pass ID through URL to "UserInfo.js", next I'm trying to get this ID in "GetUser.js" and by this ID ask API to show me informations (such as login, id, etc.) from DataBase. I have problem with React. API works fine in swaggerUI.

Code of GetUser.js:

import React,{ Component } from 'react';
import { stringify } from 'uuid';
import UserInfo from './UserInfo';


export class GetUser extends Component{
    constructor(props){
        super(props);
        this.state = { 
            id: null,
            userTable: [],
        };
    }

    componentDidMount(){
        var test = <UserInfo/>;
        this.state.id = test;
        this.GetUserById();
    }

    GetUserById(){
        let id;
        fetch(process.env.REACT_APP_API+'User/'+{id},{
            method:'GET',
            header:{'Accept':'application/json',
            'Content-Type':'application/json'}
        })
        .then(response=>response.json())
        .then(data=>{
            this.setState({userTable:data});
        });
    }

    render(){
        return(this.state.id)
    }
}

Code of UserInfo.js

import React from 'react';
import { useParams } from 'react-router-dom';

function UserInfo(){
    let { id } = useParams();

    return (id);
}
export default UserInfo;

Routing:

import React, {Fragment} from 'react';
import {BrowserRouter as Router, Route, Routes} from 'react-router-dom';
import {LoginPage} from './LoginPage';
import {Home} from './Home';
import UserInfo from './UserInfo';
import {Users} from './Users';
import {AddUser} from './AddUser';
import {GetUser} from './GetUser';
import {Profile} from './Profile';

function Routers() {
  return (
    <Router>
      <Fragment>
          <Routes>
            <Route exact path='/' element={<LoginPage/>}/>
            <Route exact path='/Home' element={<Home/>}/>
            <Route exact path='/Uzytkownicy' element={<Users/>}/>
            <Route path='/DodajUzytkownika' element={<AddUser/>}/>
            <Route exact path="/Uzytkownicy/:id" element={<GetUser/>} component={UserInfo}/>
            <Route path='/Profil' element={<Profile/>}/>
          </Routes>
      </Fragment>
    </Router>
  );
}

export default Routers;

Only what I got from console is "[object Object]" or errors of Hooks Picture of errors in network