We have an Azure AD app used for authenticating to APIs. We use permissions like offline_access, openid, profile, User.Read etc. and have granted admin consent already. This has been working since 1 year without any issues. In this week, we received 4-5 external users complaining about the error:
Need admin approval
App needs permission to access resources in your organization that only an admin can grant. Please ask an admin to grant permission to this app before you can use it.
It is not related to a particular external user from a particular organization, some other user from the same organization don't get this error.
This error occurs only for new external users, we haven't yet received any issues from existing external users.
Admin granted admin consent again after reported error but the users still get the same error message.
I went through few other questions with same error. But since the configuration has been working since past year I am bit confused. During this period we have had lot of external users without any issue.
What configuration should I check to resolve this? Or is there any update in Azure AD default settings?

