Laravel 8 - back()->withInput() is empty

If I execute a "redirect () -> back () -> withInput ()" in my controller, I do not get an old () value in my template. The -> with () errors are also not passed.

What could be the reason? My codes:

LoginController.php

class LoginController extends Controller
{
    public function login()
    {
        return view("auth.login");
    }

    public function loginPost(Request $request)
    {
        $User = User::where("email", $request->get("mail"))->first();

        if($User == null)
        {
            return redirect()->back()->with('emailError', 'No account with this email.')->withInput();
        }

        if(!Hash::check($request->get("password"), $User->password))
        {
            return redirect()->back()->with('passwordError', 'Wrong password')->withInput();
        }

        if($User->activated == 0)
        {
            return redirect()->back()->with('emailError', 'Your account is blocked.')->withInput();
        }

        Auth::login($User, true);
        return redirect()->route("user.home");
    }
}

login.blade.php

<form method="POST" action="">
                    @csrf
                    <div class="form-group">
                        <label for="inputEmail">Mail adress:</label>
                        <input type="email" name="mail" class="form-control" id="inputEmail" aria-describedby="emailHelp" placeholder="Your mail" value="">

                        @if (Session::has('emailError'))
                        <div id="phoneError" class="formError row fg-align-items-center" style="margin-top:5px;">
                            <i class="fas fa-exclamation-triangle"></i>
                            <span class="errorText"></span>
                        </div>
                        @endif
                    </div>

                    <div class="form-group">
                        <label for="inputNumber" style="margin-top:15px;">Password:</label>
                        <input type="password" name="password" class="form-control" id="inlineFormInputGroupUsername" placeholder="*****">

                        @if (Session::has('passwordError'))
                        <div id="phoneError" class="formError row fg-align-items-center" style="margin-top:5px;">
                            <i class="fas fa-exclamation-triangle"></i>
                            <span class="errorText"></span>
                        </div>
                        @endif
                    </div>

                    <div class="row form-group fg-justify-content-center">
                        <button type="submit" class="btn btn-primary" style="margin-top:15px;width:120px;">Log in</button>
                        <a href=""><button type="button" class="btn btn-primary" style="margin-top:15px;width:120px;margin-left:20px;">New here?</button></a>
                    </div>
                </form>

web.php (Routes)

Route::get('/login', [App\Http\Controllers\LoginController::class, 'login'])->name('login')->middleware('guest');
Route::post('/login', [App\Http\Controllers\LoginController::class, 'loginPost'])->name('login')->middleware('guest');

What is the reason for the malfunction?

source https://stackoverflow.com/questions/69334697/laravel-8-back-withinput-is-empty