Find another rule
Configurable

ReplaceTwigExtensionRector

Replace deprecated twig_extension() with the '.html.twig' string literal

-$ext = twig_extension();
+$ext = '.html.twig';

Configure your rector.php:

<?php

use DrupalRector\Drupal11\Rector\Deprecation\ReplaceTwigExtensionRector;
use DrupalRector\Rector\ValueObject\DrupalIntroducedVersionConfiguration;
use Rector\Config\RectorConfig;

return RectorConfig::configure()
    ->withConfiguredRule(ReplaceTwigExtensionRector::class, [
        new DrupalIntroducedVersionConfiguration('11.3.0'),
    ]);