When add-ons were published in the Chrome Web Store, the listing had a version number that could be different than the version number of the Apps Script project. Now, the only version number that I can see is the version number of the Apps Script project that must be manually entered into the configuration page of the G Suite Marketplace configuration page.
Previously, the version number in the G Suite Marketplace configuration page was automatically updated, but now it seems that you must manually update the version number yourself.
I just installed my add-on from a different Google account (free/consumer) than the add-on is published from, and I didn't see anything that shows a version number to the user. I have a hard coded version number in my add-on, so I can see whether the published version is the version that I expect.
There was a issue on the Issue Tracker
About the version number not being updated, which now has a status of "fixed." But that issue dealt with the automatic change, which now seems to be deprecated.
Those are my observations, just for the sake of keeping up with what's new.