The topic comes up often. I get (kind of) why it happens, but it is problematic when managing machines with Landscape. Having hundreds of machines reporting updates available (and, thus, missing), but not really, because they are deferred, is truly a nightmare. Is there a solution at hand for this?
I believe I have my machines sync’d based on a web search: I copied /etc/machine-id from one to all the others.
You have the info here: Phased updates in APT in 21.04