"az ad app permission admin-consent" returns "service unavailable" when logged with a service principal

[G0t-t0]

az feedback auto-generates most of the information requested below, as of CLI version 2.0.62

Describe the bug
"az ad app permission admin-consent" returns "service unavailable" when logged in with a service principal but works fine with a regular user.

To Reproduce
I guess just launch the following command line while logged in with a service principal :

az ad app permission admin-consent --id {}

Expected behavior
To actually validate the grants in the api permissions section of the app in the active directory

Environment summary

Ubuntu Bullseye - bash for windows
azure-cli versions : {                                 
  "azure-cli": "2.14.0",          
  "azure-cli-core": "2.14.0",     
  "azure-cli-telemetry": "1.0.6", 
  "extensions": {}                
}   

Additional context

• Both the user used to test and the service principal are global administrator on the Active Directory.
• it's an active directory B2C
• the whole app and its apis were created by the same service principal using the graph api

[yonzhan]

az ad

[jiasli]

Please see #12137 (comment) for the explanation and workaround.