The multi window controls become more unintuitive in iPadOS
When you want to make a floating window fixed on one side to make split screen, you have to drag it far toward the bottom corner to make the system recognize your intention, otherwise it does nothing other than showing some fancy animation and the window goes back on floating. Before the update the same action only needs you to pull the floating window downwards a bit on the top handle and it becomes fixed in split screen immediately. Besides, the split screen starts with 1:1 split rather than 3:1, another change not mentioned in the reviews.
I don’t know why apple thinks this change is for the better, the new way of doing this operation is definitely harder to discover for new users on their own.