Detected some new vm sizes during 4.16 testing, those are confidential vm supported, and its ConfidentialComputingType is 'Intel TDX', see azure doc[1]
- DCesv5-series
- DCedsv5-series
- ECesv5-series
- ECedsv5-series

e.g:
$ az vm list-skus -l westeurope --size Standard_DC8eds_v5 --query "[].capabilities[?name=='ConfidentialComputingType'].value" -otsv
TDX


When creating cluster on those vm sizes and enabling confidential settings in install-config, continued creating manifests and got below error:
install-config:
===============
compute:
- architecture: amd64
  hyperthreading: Enabled
  name: worker
  platform:
    azure:
      type: Standard_DC4es_v5
      settings:
        securityType: ConfidentialVM
        confidentialVM:
          uefiSettings:
            secureBoot: Enabled
            virtualizedTrustedPlatformModule: Enabled
      osDisk:
        securityProfile:
          securityEncryptionType: VMGuestStateOnly
  replicas: 3
controlPlane:
  architecture: amd64
  hyperthreading: Enabled
  name: master
  platform:
    azure:
      type: Standard_DC8eds_v5
      settings:
        securityType: ConfidentialVM
        confidentialVM:
          uefiSettings:
            secureBoot: Enabled
            virtualizedTrustedPlatformModule: Enabled
      osDisk:
        securityProfile:
          securityEncryptionType: VMGuestStateOnly
  replicas: 3

$ ./openshift-install create manifests --dir ipi       
INFO Credentials loaded from file "/home/fedora/.azure/osServicePrincipal.json" 
ERROR failed to fetch Master Machines: failed to load asset "Install Config": failed to create install config: [controlPlane.platform.azure.settings.securityType: Invalid value: "ConfidentialVM": this security type is not supported for instance type Standard_DC8eds_v5, no support for AMD-SEV SNP, compute[0].platform.azure.settings.securityType: Invalid value: "ConfidentialVM": this security type is not supported for instance type Standard_DC4es_v5, no support for AMD-SEV SNP] 


From installer code[2], seems only consider ConfidentialComputingType as SNP. 

[1] https://learn.microsoft.com/en-us/azure/confidential-computing/virtual-machine-options#sizes
[2] https://github.com/openshift/installer/blob/master/pkg/asset/installconfig/azure/validation.go#L220

4.16 nightly build

always

1. prepare install-config, enabling confidential settings, and set vm size to confidential vm supported and its ConfidentialComputingType is 'Intel TDX' 
2. create cluster
3.

fail to create manifests

cluster installation succeeded