How to see diff change in "Published"

Echoing this request, which seems to be a feature need— the promise "Revisions allow you to track differences between multiple versions of your content, and revert to older versions" and to then "Compare selected revisions" definitely leads one to expect that a major difference such as published versus unpublished would be shown.

Maybe the real feature need is adding all core pseudo-fields— promoted, sticky, etc as well as published?

This issue for Revision Log Default module, if implemented, would be a workaround: ✨ I want independent displays of published / unpublished status and moderation status Active

This is actually already possible by configuring the plugin to use for this field, by default it's turned off.

Go to /admin/config/content/diff/fields and change the status field to use Core field diff.