According to a Safety first article the MCDU Vapp calculation has undergone a change from older aircraft.
"AFS Computation of VAPPWhen computed by the AFS, the APPRoach CORrection (APPR COR) used by the AFS isAPPR COR = 1/3 Headwind with 5kt ≤ APPR COR ≤15 kt Excepted on some older A320 aircraft where the APPR COR used by the AFS is 1/3 Headwind + 5kt, limited at 15kt."