Steps to Reproduce:
Go into fly mode in creative mode using touch controls;
Try crouching in mid-air by pressing both ascend and descend at the same time.
Observed Results:
Fly mode is disabled, making it difficult to use fly crouch to build.
Expected Results:
Ascend & descend buttons are counted separately for the double tap action, so fly mode is disabled either when pressing ascend twice or pressing descend twice.
Notes:
This also works on activating fly mode in creative/spectator