The problem

Cant use Firebase provided private key encoded with Symfony's new secret encryption system

Details

I dont like to keep Firebase keys in json file. It would be much better to provide them in configuration file as encrypted env variables encoded with Symfony's secret management system. In config/packages/firebase.yaml instead of credentials value set to json file I tried to provide list of the values directly:

    my_project:
      default: true
      public: true
      credentials:
        type: "service_account"
        project_id: "my_project_id"
        private_key_id: 'my_project_private_key_id'
        private_key: 'my_project_private_key'
        client_email: 'my_project_client_email'
        client_id: 'my_project_client_id'
        auth_uri: "https://accounts.google.com/o/oauth2/auth"
        token_uri: "https://oauth2.googleapis.com/token"
        auth_provider_x509_cert_url: "https://www.googleapis.com/oauth2/v1/certs"
        client_x509_cert_url: 'my_project_cert'

If values are set directly here - it works.

The next step would be to encode these vars ant provide them in bundles yaml file with '%env(MY_VAR)%'.
But there is an issue with private_key value. After I tried to send push notification this warning is received: Warning: openssl_sign(): supplied key param cannot be coerced into a private key.

As I understand the issue here is because of newline character \n in this private key. Example: https://i.imgur.com/83eDkL8.png
But because it is used in yaml, I cant use str_replace to change them. Is there a way to use this key encoded?