When pressing shift to leave a boat at speeds high enough for your hands to be lowered, your hands do not come back up when outside of the boat. Although you can still destroy blocks, placing/interacting doesn't appear to work.

If coming to a complete stop (or slow enough fro your hands to be raised) before exiting the boat, the game works as intended.

There doesnt seem to be a way to fix the issue besides reloading the world.