Azure B2C SSO returning No_Oauth_Token: Access token was not returned

Hi everyone! I'm facing a weird issue.

I have an AuthProvider configured with Azure B2C. It was working perfectly fine until 3 days ago. Out from nowhere we started to receive this error after input the username/password on b2c screen: No_Oauth_Token: Access token was not returned We haven't changed anything in salesforce nor b2c (at least not that we are aware of).

Is anyone familiar with this error? Any clues?