Man pages matching name plack::middleware::header in section 3pm:

Plack::Middleware::Header.3pm.en	debian 10 / libplack-middleware-header-perl
Plack::Middleware::Header.3pm.en	debian 11 / libplack-middleware-header-perl
Plack::Middleware::Header.3pm.en	debian 12 / libplack-middleware-header-perl