Man pages matching name http::headers::actionpack::core::baseauthheader in section 3pm:

HTTP::Headers::ActionPack::Core::BaseAuthHeader.3pm.en	debian 10 / libhttp-headers-actionpack-perl
HTTP::Headers::ActionPack::Core::BaseAuthHeader.3pm.en	debian 11 / libhttp-headers-actionpack-perl
HTTP::Headers::ActionPack::Core::BaseAuthHeader.3pm.en	debian 12 / libhttp-headers-actionpack-perl