After updating Symfony from 5.4 to 6.4 routing.yml stoped working

I have a project legacy that I have been updating since symfony 2. Now I am at 6.4 however my routes stoped working.

In my routing.yml i am trying to fix the routes in the Admin folder.
Following the documentation https://symfony.com/doc/6.4/routing/custom_route_loader.html
but is not working.

I have tried:

app_admin:
  resource: ../../src/AppBundle/Controller/Admin/
  type: attribute

And the error is:

In FileLoader.php line 182:
                                                                                                                                                                                                                       
  Warning: Array to string conversion in app/config/../../src/AppBundle/Controller/Admin/ (which is being imported from app/config/routing.yml"). Make sure there is a loader supporting the "attribute" type.                                                                                                                         
                                                                                                                                                                                                                       

In AttributeClassLoader.php line 219:
                                       
  Warning: Array to string conversion  
                                       

I also have tried:

app_admin:
  # loads routes from the PHP attributes of the controllers found in the given PSR-4 namespace root
  resource:
    path: '../../src/AppBundle/Controller/Admin/'
    namespace: App\Controller\Admin
  type: attribute

However the $ php bin/console debug:router
does not load any routes.

If I change the routing.yml to add each class it works, but I don’t think it is the best way to do it. Adding each class is going to be a pain.

app_admin:
    resource: "@AppBundle/Controller/Admin/AdminController.php"
    type: attribute

Anyone have a clue what I am missing?