I believe it's breaking podcast feeds being served with WordPress.com, because iTunes doesn't support Let's Encrypt certificates.
https://www.dominicrodger.com/2016/02/29/lets-encrypt-itunes...
This may not affect a lot of customers (since WordPress.com doesn't support PowerPress for feed generation), but I know some podcasters create feeds by hand or with other apps.
This issue will cause at least some podcasts to disappear from iTunes without warning unless you can coordinate with Apple to fix it.