Unable to sync contacts from iCloud.

What is potentially happening here is that AddressBookSync.app is looking for a resource file (Contacts.icns) that is either missing or deliberately removed (during an macOS update) without updating the app’s internal references. The result is that sync crashes or fails silently. Reinstalling macOS doesn't always bring this file back because macOS System files are protected by SSV (Signed System Volume), and reinstallation doesn't always refresh those granular resource files unless you're doing an Erase & Install or a full IPSW restore.

However, there are a few options you can try before attempting a full erase & fresh macOS re-install:

Option #1 - Check if Contact sync works in Safe Mode:

• Boot into Safe Mode and try syncing again. If it works, there may be a background process or third-party plugin interfering in normal mode.

Option #2 - Check if Contact sync works with another user account:

• Create a temporary test user account, sign in to iCloud, and test Contact sync. If it works there, the issue may be localized to your main user account's ~/Library/Application Support/SyncServices or related caches.

Option #3 - You can try a "clean slate" reset of your local iCloud Contacts sync:

1. Open Terminal and run: tccutil reset AddressBook
2. Quit Contacts.
3. In Finder, go to ~/Library/Application Support/AddressBook/ and temporarily move this folder to Desktop as a backup.
4. Reboot your Mac.
5. Open Contacts again and let it re-sync from iCloud.

Sorry, none of those options worked for you. The only thing else I can suggest it that you contact Apple Support directly for further assistance with this issue.

Note that I'm assuming when you stated that you already re-installed macOS, that you did a complete erase & full fresh install of Sequoia ... correct?