This issue occurs when your Focus mode API is unable to communicate with your iCloud servers. How to fix ‘Focus Syncing Requires an iCloud Account’ on iOS 15 Ensure that you are signed in with the same iCloud account on all your other devices as well Sign out and sign back into your iCloud account
Reboot your device and Toggle On Focus/DND How to fix ‘Focus Syncing Requires an iCloud Account’ on iOS 15.