PHPDumper throws error on installation, string:OAUTH2_ENCRYPTION_KEY are never used

[crtl]

When installing the bundle and executing the symfony recipe I got following error:

 [KO]
Script cache:clear returned with error code 1
!!
!!  In PhpDumper.php line 395:
!!                                                                                                                        
!!    Environment variables "string:OAUTH2_ENCRYPTION_KEY" are never used. Please, check your container's configuration.  
!!                                                                                                                        
!!
!!
Script @auto-scripts was called via post-update-cmd

Installation failed, reverting ./composer.json and ./composer.lock to their original content.

EDIT
The error also shows when running php bin/console.

Removing string: prefix solves the issue.

composer.json

    "require": {
        "php": "^7.4",
        "ext-ctype": "*",
        "ext-iconv": "*",
        "ext-json": "*",
        "beberlei/doctrineextensions": "^1.2",
        "dragonmantank/cron-expression": "^3.1",
        "facebook/graph-sdk": "^5.7",
        "google/apiclient": "^2.2",
        "guzzlehttp/guzzle": "^7.3",
        "hidehalo/nanoid-php": "^1.1",
        "intervention/image": "^2.4",
        "jenssegers/optimus": "^1.0",
        "joshtronic/php-loremipsum": "^1.0",
        "kreait/firebase-bundle": "^2.4",
        "kreait/firebase-php": "^5.20",
        "laminas/laminas-diactoros": "^2.6",
        "league/oauth2-server": "^8.3",
        "nelmio/cors-bundle": "^2.1",
        "nyholm/psr7": "^1.4",
        "ramsey/uuid-doctrine": "^1.5",
        "sensio/framework-extra-bundle": "^5",
        "shivas/versioning-bundle": "^4.0",
        "steverhoades/oauth2-openid-connect-server": "^2.0",
        "stof/doctrine-extensions-bundle": "^1.6",
        "symfony/console": "5.3.*",
        "symfony/dotenv": "5.3.*",
        "symfony/event-dispatcher": "5.3.*",
        "symfony/flex": "^1.1",
        "symfony/form": "5.3.*",
        "symfony/framework-bundle": "5.3.*",
        "symfony/intl": "5.3.*",
        "symfony/monolog-bundle": "^3.3",
        "symfony/orm-pack": "^2.1",
        "symfony/psr-http-message-bridge": "^2.1",
        "symfony/runtime": "5.3.*",
        "symfony/security-bundle": "5.3.*",
        "symfony/serializer": "5.3.*",
        "symfony/swiftmailer-bundle": "^3.2",
        "symfony/translation": "5.3.*",
        "symfony/twig-bundle": "5.3.*",
        "symfony/validator": "5.3.*",
        "symfony/webpack-encore-bundle": "^1.5",
        "symfony/yaml": "5.3.*",
        "willdurand/negotiation": "^3.0"
    },