I'm inclined to think it may NOT be Verboeket. Although he used green and cobalt blue together for these sort of 'stretched vases it's normally a darker green than the photo reflects, (I never saw a verified example with the yellow addition), most KU examples ARE marked, and most are derived from 'standard' basic forms which this one doesn't fit, and lastly it has rather too many colour strands for the Maastricht style.
It's only a non-specific and humble opinion though!