I have a Macintosh with multiple versions of PHP. There is the default Mac version in /usr/bin/php as well as a number of alternative versions in various Web Server packages such as XAMPP and MAMP ...
The loaded rulesets seems to be PHP-executing version specific, while composer itself is not. My composer.json has platform.php '8.3.0' set. My default PHP is 8.0 The config should be loaded ...