Laravel error on logout

I have a custom AppUserProvider to fetch my users from a cache setup like so:

class AppUserProvider extends \Illuminate\Auth\EloquentUserProvider {

    public function retrieveById($identifier)
    {
        return \App\Models\User::getById($identifier);
    }
}

I then set a custom property on it in the getById method after retrieving the object with Eloquent and return it.

$user->test = 'test';

Everything works fine, but when I hit logout I get an error.

update `users` set `test` = ?, `remember_token` = ?, `updated_at` = ? where `id` = ?')

Not sure why it's trying to update the test parameter.