Backup and restore operations in Veeam Backup for Microsoft 365 fail with the error:
"The remote server returned an error: (403) Forbidden. Access denied"
Users must upgrade to latest version with Veeam Backup for Microsoft 365 5b cumulative patch KB4135.
The newest product build leverages different API queries which help to avoid the permission issue which takes place in older builds.
If after upgrading to Veeam Backup for Microsoft 365 5b (188.8.131.52) the error still occurs please create a support case and provide a full log bundle.
This form is only for KB Feedback/Suggestions, if you need help with the software open a support case