This cultivar is a recent introduction and originated from Mr. Josef Hahnl, Chorherrn, Austria. On initial inspection the leaf shape bears a striking resemblance to that of Ginkgo biloba  'Jagged Jade' (see image below). Not that I am suggesting that they are one of the same!
 
Description - Ginkgo biloba ‘Curly Leaves’. The leaves are 12cm in size, the lamina is undulating, deep green, each with one or two smaller incisions and a wavy outer edge. The annual growth rate is 30cm, therefore the plant is expected to be 3m at 10 years of age. But no comment can be made as to the eventual height and spread. 
  
Acknowledgement - Bindewald, Dr. M. 2020. for the images of Ginkgo biloba ‘Curly Leaves’.