I use always the function "switching sneaking and jumping" . In the past (before at least 1.21) only these two buttons were switched. The two buttons for swimming and flying (up and down) were still both on the right side. You could use the cross on the left to move in the right direction with left hand and the up/down button with right hand to swim or fly up or down. 

With version 1.21 the buttons of swimming up and flying up moved with activating the action to the control cross on the left.

1. I expect that only the sneak and jump button switches
2. Using the fly and swim button together with the control cross is not practical with only two hands
3. Using the swimming up and forward button does not work correctly

I hope that this will be undone.