Due to the new tree models, it was likely necessary to recalculate the data that populates them. The relationship with Blackshark seems to be gone with the new sim, so it follows that a new algorithm was developed that performs differently. But also keep in mind that the previous sim data was likely modified in many areas to correct the data and this work may not have been able to be migrated.
So we may have to wait for adjustments to be made and the worldwide data to be updated to see any improvements. Best to be patient.