See https://github.com/flutter/engine/blob/eaf70ca01903d25f2cd7aad2f0f9ce754e1e0e62/shell/platform/android/io/flutter/view/AccessibilityBridge.java#L268-L273.

As of Android 11 newer versions of TalkBack may not announce the message provided to the TYPE_WINDOW_STATE_CHANGED event. The alternative way for announcing tooltips is TBD. We may have to look at the Android source to see how the a11y for the native tooltip works or reverse-engineer the right way from TalkBack's debug logs when activating a native tooltip.