Hi @Manish Aery ,
As per my research the signed in user must be global admin/ privileged admin to do this operation. Along with Directory.ReadWrite.All/ Group.ReadWrite.All we should configure RoleManagement.ReadWrite.Directory permission also. Please find the below screenshot also
Could you please check the user role and permission and update mailEnabled property to false. If you are still facing this issue , I would advise you to raise a support case with Microsoft Graph, a specialized Support Engineer will be able to assist you better.
You can raise technical support request from:
https://portal.azure.com/#view/Microsoft_Azure_Support/HelpAndSupportBlade/~/overview or https://admin.microsoft.com/#/support/requests.
Hope this helps.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".