Since upgrading to Composer 2, Extensions catalog throws error:

Fatal error: Uncaught Error: Call to private method Composer\Repository\ComposerRepository::hasProviders() from scope phpbb\composer\installer in [ROOT]\phpbb\composer\installer.php on line 304

The reason is that ComposerRepository::hasProviders() was made private since Composer 2.

Steps to reproduce:

Go to ACP/Customize/Extensions catalog, if you don't get the error, go to -> Settings -> choose Minimum stability: dev, save settings and visit Extensions catalog again.