Even with a perfect link, some things are tied to your device identifier (Advertising ID) and not your account.
Confirm the action to overwrite the local tutorial data and download your high-level account. Troubleshooting Common Save Data Sync Issues angry birds 2 save data link
To secure your Angry Birds 2 progress, you must link your game to a third-party account. This acts as a "save data link," allowing you to sync progress across multiple devices and recover your account if you lose access to your phone. Methods to Link Save Data Even with a perfect link, some things are
If the Facebook link fails, log out of Facebook in your browser and try connecting again within the app. Even with a perfect link