Advanced data protection compatibility with older Mac OS

Looking at the software requirements for the iCloud advanced data protection it states that you need iOS 16.2 and macOS 13.1 or newer.

My question is if the iCloud Drive data will remain available and synchronized when a Mac - iPhone or iPad isn’t on the required minimum version of the operating system.

I called Apple support and no one seems to have an answer…

As far as I understand Advanced Data Protection, you can’t activate this feature if any Apple device with a system below the minimum requirements is logged in into iCloud. So you will probably have to log out your old devices out of iCloud first, and then you probably won’t be able to log in with them again.

Yea, it’s really strict about enabling it. My wife’s phone is signed into Apple Music with my account, and since the music is synced to her Apple Watch Series 3, and since the Series 3 is not capable of running the latest WatchOS, I can’t enable ADP. At least not till I either sign her out of my account or upgrade her watch.

I also tried setup the advanced data protection and was stopped by the requirement to update my devices or remove them from the account. Even the HomePod needs to be updated.

Concerning is that my old MB Pro running High Sierra is not showing on the list despite being signed into the same Apple ID

I would like to turn on Advanced Data Protection, but am running a MacBook Pro laptop (Monterey 12.6.3) as a home server. Does anyone know what the implications are of removing that device from my account (so I can turn on ADP)? Can I still continue to use the device as a sever and connect to it? Do I just lose access to mail, messages, etc?