[romjak]

Some other items that get synced through iCloud are phone numbers and emails of people you text, or send email to, even if they are not in your address book. Searches you put into Maps are also synced this way as far as I know.

Most of this data can be viewed on a macOS if you are signed in with the same iCloud account. It is stored in plist-files in a special folder called "SyncedPreferences".

~/Library/SyncedPreferences ~/Library/Containers/com.apple.corerecents.recentsd/Data/Library/SyncedPreferences

It has bothered me for a long time that there is no way to disable call log, text and email recipients syncing in preferences. While I can see how users might find this feature useful, it should be made more obvious what is actually happening when you sign into iCloud.

And by the way, disabling iCloud Drive does not disable the syncing of "SyncedPreferences".