1) templating
This is due to the deprecation of the templating component, see https://symfony.com/blog/new-in-symfony-4-3-deprecated-the-templating-component-integration

Solution:

    Remove "symfony/templating" from composer.json
    Remove this from framework.yaml:

    templating:
        engines:
            - twig

    Run composer update

This should remove all the deprecation warnings.

If you're getting this error

    Cannot autowire service "...": argument "$templating" of method "__construct()" references interface "Symfony\Bundle\FrameworkBundle\Templating\EngineInterface" but no such service exists. Did you create a class that implements this interface?

... you're still using the old templating in some service.
Solution: Change the dependency from Symfony\Bundle\FrameworkBundle\Templating\EngineInterface to Twig\Environment:

use Twig\Environment;

private $twig;

public function __construct(Environment $twig)
{
    $this->twig = $twig;
}

See also https://github.com/symfony/symfony/issues/31645