Man pages matching name plack::handler::net::async::fastcgi in section 3pm:

Plack::Handler::Net::Async::FastCGI.3pm.en	debian 10 / libnet-async-fastcgi-perl
Plack::Handler::Net::Async::FastCGI.3pm.en	debian 11 / libnet-async-fastcgi-perl
Plack::Handler::Net::Async::FastCGI.3pm.en	debian 12 / libnet-async-fastcgi-perl