Auth::user() empty, using custom user provider

Hello, Using Laravel 10 i'm setting up a custom user provider, because i'm using an SSO service (CAS), the user provider i wrote just fetch the currently logged in user (via subfission\cas module) and instantiate and return the corresponding model so it can be accessed by Auth::user().

the steps i've taken:

• Create a model which implements the Illuminate\Contracts\Auth\Authenticatable interface (i do keep some user related infos in local DB but Authentication doesn't take place here):

use Illuminate\Foundation\Auth\User as BaseUser;
use Illuminate\Contracts\Auth\Authenticatable;


class User extends BaseUser implements Authenticatable
{
    use HasFactory;

    protected $table = 'user';

 public function getAuthIdentifierName() {
        return 'uid';
    }

    public function getAuthIdentifier() {
        return app('cas')->user();
    }

    public function getAuthPassword() {
        return null;
    }
    public function getRememberToken() {
        return null;
    }
    public function setRememberToken($value) {

    }

    public function getRememberTokenName() {
        return null;
    }

• Create a custom user provider which returns instances of the above model:

namespace App\Providers;

// use Illuminate\Support\ServiceProvider;
use Illuminate\Contracts\Auth\UserProvider;
use Illuminate\Contracts\Auth\Authenticatable;
use App\Services\UserService;
use App\Models\User;


class CasUserProvider implements UserProvider
{
    public function __construct(UserService $user_service) {
        $this->user_service = $user_service;
    }

    public function retrieveById($identifier): ?Authenticatable {
        $uid = app('cas')->user();
        $user = $user_service->findByUid($uid);
        return $user;
    }

    public function retrieveByToken($identifier, $token): ?Authenticatable {
        $uid = app('cas')->user();
        $user = $user_service->findByUid($uid);
        return $user;
    }

    public function updateRememberToken(Authenticatable $user, $token) {

    }

    public function retrieveByCredentials(array $credentials): ?Authenticatable {
        $uid = app('cas')->user();
        $user = $user_service->findByUid($uid);
        return $user;
    }

    public function validateCredentials(Authenticatable $user, array $credentials) {
        return true;
    }
}

• Register it in AuthServiceProvider:

public function boot(): void
    {
        Auth::provider('cas_user', function (Application $app, array $config) {
            return new CasUserProvider(new UserService());
        });
    }

• Adding the provider in conf\auth.php and set the default 'web' guard to use it:

'defaults' => [
        'guard' => 'web',
        'passwords' => 'users',
    ],

'guards' => [
        // conf par défaut
        'web' => [
            'driver' => 'session',
            'provider' => 'cas_users',
            // 'credentials' => [
            //     'email' => 'login',
            //     'password' => 'password'
            // ]
        ],

    ],

'providers' => [
        // conf par défaut
        'users' => [
            'driver' => 'eloquent',
            'model' => App\Models\User::class,
        ],

        'cas_users' => [
            'driver' => 'cas_user',
        ],

    ],

The Auth is done via a middleware and this part is working, also i don't get any errors, but calls to Auth::user() in controllers, or auth()->user() in blade templates always yield empty result. Any help would be greatly appreciated