Man pages matching name config::model::backend::approx in section 3pm:

Config::Model::Backend::Approx.3pm.en	debian 10 / libconfig-model-approx-perl
Config::Model::Backend::Approx.3pm.en	debian 11 / libconfig-model-approx-perl
Config::Model::Backend::Approx.3pm.en	debian 12 / libconfig-model-approx-perl