Unfortunately, this is the default behavior with macOS when you issue a device wipe command. As you can see in the MDM developer documentation (https://developer.apple.com/documentation/devicemanagement/erasedevicecommand/command?changes=latest_minor ), there is no option to preserve the recovery partition. The only "data preservation" key is for Data Plan information (for cellular-enabled devices). If you need an option to preserve the recovery partition, i suggest you file feedback in the "Feedback Assistant" if you're testing the macOS Big Sur developer beta.
An alternative that I've seen folks exploring is to instead redistribute the macOS Installer. You can basically accomplish an automated rebuild by scripting a combination of the following:
1). /usr/sbin/softwareupdate --fetch-full-installer
Use this command to pull down the latest installer file from the client. (alternatively, you could skip this step and instead push either the VPP-based installer or push the full installer). This gets you the install bits and the command you need in the next part. Note, some builds of macOS support fetching a specific macOS version using the --fetch-installer-version parameter.
2). '/Applications/Install macOS Catalina.app/Contents/Resources/startosinstall' --eraseinstall --agreetolicense --forcequitapps --newvolumename 'Macintosh HD'
This command tells the installer to create a new partition and copy the installer to the new partition, reboot and erase the current disk, and then re-install macOS where the old partition used to be.
Hope that helps!
Thank you so much for the detailed reply, I'll check out your suggestions.