Laravel: Deploying without "facade/ignition" composer dependency results in Class "Facade\Ignition\IgnitionServiceProvider" not found error

Question

I'm on Laravel 8. In my composer.json file there is this:

"require-dev": {
 "facade/ignition": "^2.5",
 ....
},

Without facade/ignition, my website always shows me this error:

(Symfony Exception)
HTTP 500 Internal Server Error
Class "Facade\Ignition\IgnitionServiceProvider" not found

So when I deploy with "composer install --no-dev" (and thus, missing "facade/ignition package") I get the error.

Furthermore, when I try to upgrade to Laravel 9 and replace facade/ignition with "spatie/laravel-ignition": "^1.0" - I also get this error. So I cannot upgrade to Laravel 9 atm.

I tried everything StackOverflow & co suggested:

• delete ./vendor folder
• composer install
• composer update
• composer dump-autoload

I can't escape the error.

My complete composer.json file:

{
    "name": "laravel/laravel",
    "description": "The Laravel Framework.",
    "keywords": ["framework", "laravel"],
    "license": "MIT",
    "type": "project",
    "require": {
        "php": "^7.3|^8.0",
        "ext-curl": "*",
        "ext-dom": "*",
        "ext-json": "*",
        "ext-libxml": "*",
        "abraham/twitteroauth": "^2.0",
        "barryvdh/laravel-debugbar": "^3.0",
        "beyondcode/laravel-websockets": "1.*",
        "doctrine/dbal": "^2.8",
        "fideloper/proxy": "^4.0",
        "fruitcake/laravel-cors": "^2.0",
        "guzzlehttp/guzzle": "^7.0.1",
        "intervention/image": "^2.5",
        "kreait/laravel-firebase": "^2.1",
        "laravel/framework": "^8.0",
        "laravel/helpers": "^1.4",
        "laravel/tinker": "~2.0",
        "laravel/ui": "^3.0",
        "league/flysystem": "1.1",
        "league/flysystem-aws-s3-v3": "~1.0",
        "mailjet/mailjet-apiv3-php": "^1.5",
        "predis/predis": "^1.1",
        "pusher/pusher-php-server": "~4.0",
        "sentry/sentry-laravel": "^2.3",
        "spatie/laravel-backup": "7.0",
        "spatie/laravel-sitemap": "^5.5",
        "staudenmeir/eloquent-eager-limit": "^1.0",
        "stevebauman/location": "^5.0",
        "tgalopin/html-sanitizer": "^1.3"
    },
    "require-dev": {
        "facade/ignition": "^2.5",
        "fzaninotto/faker": "~1.4",
        "mockery/mockery": "0.9.*",
        "nunomaduro/collision": "^5.0",
        "phpunit/phpunit": "^9.0"
    },
    "autoload": {
        "psr-4": {
            "App\\": "app/",
            "Database\\Factories\\": "database/factories/",
            "Database\\Seeders\\": "database/seeders/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "Tests\\": "tests/"
        },
        "files": ["tests/Utilities/functions.php"]
    },
    "scripts": {
        "post-root-package-install": [
            "php -r \"file_exists('.env') || copy('.env.example', '.env');\""
        ],
        "post-create-project-cmd": [
            "php artisan key:generate"
        ]
    },
    "config": {
        "preferred-install": "dist",
        "sort-packages": true,
        "optimize-autoloader": true
    }
}