Web Part SPFX Yammer User Impersonation Error Issue

Question

I developed a webpart which uses the following configuration to being enabled to call Yammer:

{
    "resource": "Yammer",
    "scope": "user_impersonation"
}

Now the problem is that on the DEV tenant I succeed at granting the API permissions to it, whereas on the PROD tenant I receive the following error.

Is anyone able to explain me what's going on and how to fix that?