use strict;
use warnings;
use Pod::Simple::XHTML;

STDOUT->binmode(':encoding(UTF-8)');

# pretend that HTML::Entities isn't installed
$Pod::Simple::XHTML::HAS_HTML_ENTITIES = 0;

my $p = Pod::Simple::XHTML->new;
$p->parse_file(\*DATA);

__DATA__
=encoding utf8

=head1 NAME

ąść

=cut

The above code outputs "ąść" literally. When you flip $Pod::Simple::XHTML::HAS_HTML_ENTITIES to 1, non-ASCII characters get escaped using HTML entities.

Pod::Simple::XHTML should escape the same set of characters regardless of whether HTML::Entities is installed or not.

BTW, this bug is the most likely reason why GitHub doesn't render non-ASCII characters in Pod documents correctly.