Composer versions 2.2.0 and 2.2.1 have a bug that breaks PHPUnit. Until version 2.2.2 is released with a fix, we need to keep to Composer 2.1 to keep the tests from breaking. See https://github.com/composer/composer/issues/10387 for details.
Co-authored-by: Łukasz Uznański <l.uznanski@macopedia.com>