Google introduced the new one Bubbles API with Android 10 Beta 2 in April last year. The API was initially offered as an activation feature for developers, with Google urging them to test the API in their apps in order to make them optimized when this function would arrive in a future version of Android.
As expected, the feature was enabled by default in Android 11 Developer Preview 1, earlier this year. Now, in the first beta, the Bubbles feature is available in Notification settings (and not in Developer Options).
To date, we have seen the feature in action only in one APK of the Google Messages app but, the latest update from Facebook Messenger makes it fully supported to the Bubbles API.
For the uninitiated, Facebook Messenger has long had a feature for mobile notification bubbles called “Chat Heads”. The function made use of the API Window Alert Window Android, but in the latest version 2184.108.40.206.118, the app switches to the new Android 11 Bubbles API.