The culprit seems to be the latest splunklib Python SDK. I'm sure it will be fine just thought I would ping the devs to either fix the warnings or get the Upgrade Readiness devs to exclude the warnings for splunklib.
An example of one of the warnings. I'd attach the full JSON output but this forum doesn't seem to allow attachments.
The Splunk Platform Upgrade Readiness App is no longer taking new updates and is replaced by the Upgrade Readiness App. The scan of the splunklib is ignored and these warnings should no longer appear in the latest version 3.0.2. Please update to using the latest Upgrade Readiness App.