Man pages matching name fennec::manual::customfennec in section 3pm:

Fennec::Manual::CustomFennec.3pm.en	debian 10 / libfennec-perl
Fennec::Manual::CustomFennec.3pm.en	debian 11 / libfennec-perl
Fennec::Manual::CustomFennec.3pm.en	debian 12 / libfennec-perl