iPad split keyboard space bar/undo too close iOS11

Since the update to iOS 11 I have experienced a maddening issue with the iPad split keyboard layout.

The space bar is a decent size until you go in to numerics, when on the left hand side it becomes minuscule and instead, just under where your thumb is, the UNDO key appears. So I accidentally delete everything I just wrote.

Surely this is a design flaw Apple?

Does anyone have a solution to this Please? It’s driving me totally crazy.

Thanks

Running IPad Pro 9” with iOS 11.4