This article explains whether mixed ESX versions are supported within a single cluster in VMware Cloud Foundation (VCF) 9.0/9.1.
VCF 9.0
VCF 9.1
Unsupported Configuration During Bring-up:
Deploying host targets with mixed ESX versions during VMware Cloud Foundation (VCF) 9.0/9.1 bring-up is not supported.
Supportability in Cluster Operations:
Running mixed ESX versions within the same cluster is not recommended, except for temporary states during the upgrade process.