Move water, sure. Cause a tsunami, sure. Cause a global flood, no. Especially not one that puts Everest under water. There isn't enough water on Earth for that.
As it should be since that land was below the ocean when the Indian plate crashed into the Asian plate. This was far back, like the timeframes it takes for things to fossilize.
This can easily be explained by a change of the earth's suface geometry (mountains height and oceans depth).A rapid change could have simply trigger mass of water to move across lands
How could that rapid change happen? Chemical differentiation happened long ago. Granite plates float of the mantel higher than basaltic plates. They dont suddenly sink into the mantle.