When moving, seemly at random or when there is a large hole somewhere nearby, the character will try to navigate down towards the bottom of the screen and will fight mouse input. This occurs when HOLDING the mouse button for movement, if clicking, the character will often momentarily flick between the direction you want it to go and down, then attempt to go to the correct tile. The character will also not attack properly and will get stuck in the bottom corners or bottom middle and be unable to move. There are youtube videos of this if you search "Minecraft Dungeons movement bug"