I found this website with what appears to be really good info on how to disable Time Machine. It's dated March 2021, so I tried the first one anyway (Prong 1), and neither the sudo command, nor the MDM Profile work. The sudo command
sudo defaults write /Library/Preferences/com.apple.TimeMachine DoNotOfferNewDisksForBackup -bool TRUE
returns "Could not write domain /Library/Preferences/com.apple.TimeMachine".
The configuration profile got installed on the machine, but after connecting an external drive, I got the prompt anyway.
I figure this is old information at this point, but does anyone have knowledge on how to do effectively disable Time Machine in its entirety? I can restrict the app, but what can be done about the popup when external drives are inserted?
No, I did not, mostly because I just haven't had the time to test further. My next test was to disable Time Machine as suggested above. Not sure that disabling it would prevent notifications after connecting an external drive. That is where I'm at.