Magento 2.4 fails to install due to missing composer config file in composer_home

I tried to install Magento 2.4 via command line. It runs smooth until

[Progress: 653 / 1206] Module 'Magento_ComposerRootUpdatePlugin': 

At this step the installation fails with

Installing data... Reading /<magento_root>/composer.json Loading config file /<magento_root>/composer.json Failed to initialize global composer: Composer could not find the config file: /<magento_root>/var/composer_home/composer.json To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section 

Composer is installed globally. The Magento documentation does not mention anything else regarding composer.

Thank you very much.

For reference: I also posted at stackexchange. People seem to face the same issue but no solution so far: https://magento.stackexchange.com/questions/318915/magento-2-4-fails-to-install-due-to-missing-composer-config-file-in-composer-hom