The InputDecorator has an AnimatedOpacity transition for hiding/showing the hint text https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/material/input_decorator.dart#L1695

However, the hint text should disappear/appear immediately upon the user entering or clearing text (or maybe make this animation configurable/optional?).

The overlapping of the hint text and the newly-entered text during the fade is a little disorienting. Compare this with native apps like Gmail or Tasks or Maps, where the hint text cuts instantly instead of fading.