I find it interesting that there is a few that keep insisting that this is not a problem and keep stirring the pot because they are the minority of the users. This will probably get deleted but users will see it in their email.
Apple likes to make things complicated, like this forum, since it got updated its a pain to navigate and the posts are not in order anymore.
The solution I found was simple for us who have two phones for work and personal, log out of your ID on your work phone, the syncing will stop. I have not had a call log sync.
If you want to add an app, log back in.
IMO there is no point in having a apple ID for the second work phone, what other data is Apple storing on their servers without users knowledge. I won’t even allow diagnostics info to be sent and I have it toggled off, maybe it is doing it anyway.