VCP5-DCV or VCP6-DCV holders don't need to attend any training as part of VCP-DCV 2019 - they just need to pass 1 exam.

VCP3 or VCP4-DCV holders have to attend a full class and pass 2 exams - the same as a newbie.

This seems entirely fair to me.

VMware Certified Professional - Data Center Virtualization 2019 (VCP-DCV 2019)