Facebook has closed their Gameroom service on June 30, 2021.

You can continue playing the game on your browser via https://apps.facebook.com/angrybirds/ 

In case you are on Windows 10 device, you can also play the standalone version that is available in the Windows 10 Store - https://www.microsoft.com/en-us/p/angry-birds-friends/9nn6g50qnl1h