Anyone found the answer on why not all contacts on your phone sync with your new one?

Here’s how you can try to fix it:

Turn on iCloud sync, please follow these steps:

1. On your iPhone, open the "Settings" app.
2. Tap on your name at the top of the screen.
3. Scroll down and tap on "iCloud".
4. Sign in with your Apple ID and password, if you haven't already.
5. Enable Contacts.
6. Wait for your iPhones to securely sync overnight on charge, make sure both of your iPhones are on the same Apple ID.

If the above steps do not help, reach out to Apple support for further assistance.

Further information: If your iCloud Contacts, Calendars, or Reminders won’t sync - Apple Support