Man pages matching name mongoc_uri_get_auth_mechanism in section 3:

mongoc_uri_get_auth_mechanism.3.en	debian 10 / libmongoc-doc
mongoc_uri_get_auth_mechanism.3.en	debian 11 / libmongoc-doc
mongoc_uri_get_auth_mechanism.3.en	debian 12 / libmongoc-doc