Symfony version(s) affected: 5.3.0-BETA2

Description
I have an application that uses a custom implementation of PasswordEncoderInterface. After upgrading that application to Symfony 5.3, I cannot log in anymore. Instead, I get the following exception:

Symfony\Component\PasswordHasher\Hasher\PasswordHasherFactory::createHasher(): Argument #1 ($config) must be of type array, App\Security\MyEncoder given, called in /path/to/encoder-reproducer/vendor/symfony/password-hasher/Hasher/PasswordHasherFactory.php on line 60

How to reproduce
See https://github.com/derrabus/encoder-reproducer for a reproducer. You should encounter the error when trying to log in. Revert the last commit ("Upgrade to Symfony 5.3") and the app works as expected.