How to get bounds of visible map with flutter google_maps plugin?

That would be GoogleMapController.getVisibleRegion()

Be careful, GoogleMapController.getVisibleRegion() returns a LatLngBounds (a rectangle) and if your map has a tilt then it should not be a rectangle but a trapezoid!

The issue is in the plugin implementation where the returned result is computed only from latLngBounds field whereas it should be computed from farLeft, farRight, nearLeft, nearRight fields. Reference: https://developers.google.com/maps/documentation/android-sdk/reference/com/google/android/libraries/maps/model/VisibleRegion

So GoogleMapController.getVisibleRegion() is not accurate and can't be used if there's a tilt.

For reference, an issue has been created: https://github.com/flutter/flutter/issues/74888