On the metaCPAN site, lookup the module. A link labelled "Issues" appears on the left.

On search.cpan.org, look up the module, and there will be a link labelled "View/Report Bugs" in the distribution page for the module.

If the module has a publicly-available repository (such as at GitHub) or website, then you may find an issue tracker, forum, or wiki with information about encountered bugs or proposed features.

Hope that helps.