second group result may be lower because ICAI wants all its studnets to be examined for GST. Do you remeber few last attempts of PE 2 exam, results were brought down to 1.5% just to force students to convert to IPCC and IPCC results were kept at 15-20%.
So in same way icai will reduce the pass percentage so that more and more students will come under new syllabus, because its needed for future