Our designers usually design IKEA kitchens from the corner outwards. It seems as if this designer had a change of heart after designing the tall corner cabinets and then went back to normal 30” high uppers.
The tall corner was intentional because it gave a little lift to the design and offers more storage space. An IKEA blind wall cabinet was chosen over a diagonal so the design kept its right angles and matched the corner below.
Please see the our previous post for more on Blind Corners