Man pages matching name date::leapyear in section 3pm:

Date::Leapyear.3pm.en	debian 10 / libdate-leapyear-perl
Date::Leapyear.3pm.en	debian 11 / libdate-leapyear-perl
Date::Leapyear.3pm.en	debian 12 / libdate-leapyear-perl