If you are registering a multi-tenant app in Microsoft Azure's App registration for granting consent for other users, you must be verified publisher. otherwise, generally no verification process required to use Microsoft Graph API.
If you plan to publish app such as Teams app, Outlook add-in to the relevant Microsoft store, there will be verification process, during this process, you might be asked to provide reason for using graph Api, mostly permissions, scopes.
I hope this helps. If the reply is helpful, please click Accept Answer and kindly upvote it. If you have additional questions about this answer, please click Comment.