Man pages matching name mongoc_read_prefs_is_valid in section 3:

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