My understanding has always been that Apple will install the most recent version of an app supported by the given version of macOS requesting the install. The app install still comes from the AppStore, not JAMF. JAMF just kicks off the workflow to install the app.

You're right that the app comes from Apple but the version that is displayed in Jamf dictates what version is installed and whether apps update to it or not. I've since discovered that you can edit the time it checks for app versions in Settings > Device Management > App Maintenance, so thats not a problem. Just frustrating that this doesn't seem to have been communicated as we had older workflows that required manual validation of versions.

To be honest I have never tried to version control an AppStore app. I am fairly strict about you get what you get and you don't pitch a fit.

Have you tried making a new AppStore App policy?

Yeah, I'm pretty sure that Apple nixes older versions on the App Store when new ones come, so you're not really going to get "control" here.  Only other thing you might want to look for is installers elsewhere (vendor) to install yourself with more control.  Apple are very much into "latest is the greatest" so you're probably fighting an uphill battle...