The ideal grip height is personal; experiment to find what feels most comfortable and effective for you, as there is no single correct position.
The coaches in this discussion offer great perspective on racket grip height. They emphasize that there's no strict rule, showing how different pros use varied grips, sometimes high, sometimes low for specific shots like the smash. It's really about finding what feels comfortable and works for your game, so feel free to experiment. Don't let anyone tell you there's only one way to do it.