Can login with tinker, not with controller

[Naghal]

I have followed the database auth configuration documentation and I can successfully login with my active directory credentials using tinker. It does sync the user in the users table in the database.

However, trying to achieve the same thing in a controller, Auth::attempt($credentials) returns false.
My App\Models\User model implements LdapAuthenticatable and uses the trait AuthenticatesWithLdap.

auth.php

'defaults' => [
        'guard' => 'web',
        'passwords' => 'users',
    ],
'guards' => [
        'web' => [
            'driver' => 'session',
            'provider' => 'users',
        ],
    ],
'providers' => [
        'users' => [
            'driver' => 'ldap',
            'model' => LdapRecord\Models\ActiveDirectory\User::class,
            'rules' => [],
            'database' => [
                'model' => App\Models\User::class,
                'sync_passwords' => false,
                'sync_attributes' => [
                    'name' => 'cn',
                    'email' => 'mail',
                    'username' => 'samaccountname'
                ],
            ],
        ],
    ],

LoginController

class LoginController extends Controller
{
    public function authenticate(AuthService $service)
    {
        $credentials = request()->validate([
            'samaccountname' => 'required',
            'password' => 'required',
        ]);
        $hasValidCredentials = $service->authenticateUsingCredentials($credentials);

        if ($hasValidCredentials) {
            request()->session()->regenerate();
            return redirect()->intended('/home');
        }
    }
}

AuthService

<?php

namespace App\Services;

use Illuminate\Support\Facades\Auth;

class AuthService
{
    public function authenticateUsingCredentials(array $credentials)
    {
        return Auth::attempt($credentials, true);
    }
}

The test that I've wrote also fails.

/** @test */
    public function a_user_can_login_using_valid_ldap_credentials()
    {
        $this->withoutExceptionHandling();
        $password = 'someValidPassword';
        $user = User::factory()->create(['password' => bcrypt($password)]);
        $credentials = [
            'samaccountname' => $user->username,
            'password' => $password
        ];

        $this->mock(AuthService::class, function(MockInterface $mock) {
            $mock->shouldReceive('authenticateUsingCredentials')->once()->andReturn(true);
        });

        $response = $this->post('/login', $credentials);
        $response->assertRedirect('/home');
        $this->assertAuthenticated();
       // $this->assertAuthenticatedAs($user);
    }

What can explain that I can login when in a tinker bash, but not from the controller?