DateTime is at 1.59 since 2022-10-23. Because you have cpan set to use strawberryperl's mirror, even though CPAN mirrors aren't recommended since the central server handles loadbalancing now, you are relying on strawberryperl being up-to-date; given that they haven't released a new version of perl since 2021, expecting their cpan-mirror to be more up-to-date than their perl version is a bit optimistic. I always use cpanm client from strawberryperl, without overriding to any mirrors, and it has no problem deciding it's time to update DateTime.

But even in v1.54's documentation, the local_day_of_week documentation matches hippo's quote. You are quoting from the SYNOPSIS, and are quoting an example of day_of_week() even though your original code used local_day_of_week(), which is a different function with different return values.