Unsync new macbook pro from old macbook pro

racheleh1 wrote:

My new macbook pro has less than half the storage of my old one and I want them to quit syncing with each other

Typically when buying a new Mac you step up to the next GB of storage available to avoid issues. This would be point of purchase only. You have a limited 14-day return policy on a new purchase for any reason, if you decide to make a change.

ref: Returns & Refunds - Shopping Help - Apple

You can sign the old Mac out of AppleID/iCloud if you do not want the sync

>System Settings>AppleID

Sign in or out of your Apple ID on Mac

Sign out of iCloud...Mac

see— What to do before you sell, give away, trade in, or recycle your ...

Once you migrate your data, ONCE, there is no connection between old Mac and new Mac.

But what might make its seem like they are connected is having both using 'Optimized storage' through your Apple-ID account.

Optimized storage is a temporary work-around. If it is not solving the ENTIRE problem for you, you will need to add an external drive to hold more files. Luckily there are some fairly portable solutions available now.

This article talks about optimizing storage space on your Mac. Keep in mind that if the setting for optimized storage is active, somewhere between some and all of the files managed may be present on your Mac, or may be available for quick download from iCloud.

Free up storage space on your Mac - Apple Support

if both the old and new Mac are also using the same technique with the same Apple-ID, any files added to the old Mac appear to be "linked" to the new Mac as well.