Man pages matching name datetime::locale::cy_gb in section 3pm:

DateTime::Locale::cy_GB.3pm.en	debian 10 / libdatetime-locale-perl
DateTime::Locale::cy_GB.3pm.en	debian 11 / libdatetime-locale-perl
DateTime::Locale::cy_GB.3pm.en	debian 12 / libdatetime-locale-perl