Man pages matching name sys::filesystem::freebsd in section 3pm:

Sys::Filesystem::Freebsd.3pm.en	debian 10 / libsys-filesystem-perl
Sys::Filesystem::Freebsd.3pm.en	debian 11 / libsys-filesystem-perl
Sys::Filesystem::Freebsd.3pm.en	debian 12 / libsys-filesystem-perl