Most probably CPANTS databases are being regenerated from scratch due to major changes in Kwalitee metrics or updates of relevant modules/perl. Usually this maintenance takes about a day or two, and some of the information may be old or missing tentatively. Sorry for the inconvenience.
Add a README to the distribution. It should contain a quick description of your module and how to install it.
Fix MANIFEST.SKIP or use an authoring tool which respects MANIFEST.SKIP. Note that each entry in MANIFEST.SKIP is a regular expression. You may need to add appropriate meta characters not to ignore necessary stuff.
Error: META.json,META.yml
Add a section called "LICENSE" to the documentation, or add a file named LICENSE to the distribution.
Add =head1 LICENSE and the text of the license to the main module in your code.
Add 'use strict' (or its equivalents) to all modules, or convince us that your favorite module is well-known enough and people can easily see the modules are strictly written.
Error: PDL::Demos::Proj4_demo
If you are using Build.PL define the {requires}{perl} = VERSION field. If you are using MakeMaker (Makefile.PL) you should upgrade ExtUtils::MakeMaker to 6.48 and use MIN_PERL_VERSION parameter. Perl::MinimumVersion can help you determine which version of Perl your module needs.
Define the license if you are using in Build.PL. If you are using MakeMaker (Makefile.PL) you should upgrade to ExtUtils::MakeMaker version 6.31.
Add =head1 LICENSE and/or the proper text of the well-known license to the main module in your code.
Add 'use warnings' (or its equivalents) to all modules, or convince us that your favorite module is well-known enough and people can easily see the modules warn when something bad happens.
Error: PDL::Demos::Proj4_demo
Add all modules contained in this distribution to the META.yml field 'provides'. Module::Build or Dist::Zilla::Plugin::MetaProvides do this automatically for you.
Add a 'repository' resource to the META.yml via 'meta_add' accessor (for Module::Build) or META_ADD parameter (for ExtUtils::MakeMaker).
This is not a critical issue. Currently mainly informative for the CPANTS authors. It might be removed later.