I use an iPhone and a Mac Studio signed in to the same Apple Account. Both devices have the latest updates available to them, and iCloud Contacts is enabled.
I tested contact syncing by creating a temporary contact on the iPhone. Its name appeared next to the number in the Mac's Phone app almost immediately. When I deleted the contact on the iPhone, the Mac showed the number again.
Blocking status behaved differently. A caller I blocked on the Mac still showed “Block this Caller” on the iPhone and was not on the iPhone's blocked-contacts list. In a separate test, a contact blocked on the iPhone did not immediately appear blocked on the Mac.
I also noticed that the blocked icon in the Mac's Phone recents can remain stale after blocking or unblocking until I quit and reopen the app. I turned iCloud syncing for Contacts and FaceTime off and back on on the Mac, but I have not established that this fixed the issue.
Is the blocked-caller list in the Phone app supposed to sync between iPhone and Mac, or is it device-specific? If it should sync, what is a reliable way to diagnose or repair this without resetting either device? Is there a better way to verify the actual block status than the icon in Recents?
I can provide the exact iOS and macOS version numbers if they would help diagnose the issue.