Man pages matching name parse::http::useragent::constants in section 3pm:

Parse::HTTP::UserAgent::Constants.3pm.en	debian 10 / libparse-http-useragent-perl
Parse::HTTP::UserAgent::Constants.3pm.en	debian 11 / libparse-http-useragent-perl
Parse::HTTP::UserAgent::Constants.3pm.en	debian 12 / libparse-http-useragent-perl