They actually sent out an announcement email to developers - the first directly communication they have sent out about anything developer related during this whole transition - but the communication was pretty vague…
“We expect most API/SDK integrations to continue to work with these new apps. While no changes have been made to our API, please be aware that there are a handful of features—such as AppleScript, import folders, and possibly some 3rd party entry points—that are not yet available.”
“We expect” and “possibly some” are not phrases which inspire confidence that they even know what they did and did not break.
I think they probably hope to replace their integration SDKs with an industry-standard REST API at some point, but at the rate they have been going, that might be years away. It’s clear they have no intention of fixing their iOS SDK, which currently would be rejected by Apple if used as-is and has a broken authentication process for some of their users.