vCert.py script from KB 385107 was successfully run to replace all certificates. However, the dates of the certificates did not change.
vCenter 8.x
A certificate's validity period cannot exceed that of the certificate authority (CA) that issued it. Specifically, the VMCA cannot sign certificates with a longer lifetime than its own. Once the root CA's validity expires, it loses the trust required to sign new certificates, and any certificates it previously signed may consequently become untrustworthy.
Select option 3 'Manage certificates' and then option 9 'VMCA certificate' to replace VMCA and regenerate all certificates as explained in kb vCert - Scripted vCenter expired certificate replacement