Sharepoint sites are skipped on veeam office 365 backup with the following warning:
Processing site https://eraorg.sharepoint.com/sites/EraTeam finished with warning: Cannot change web part export mode to ‘All’, because custom scripting is disabled for site: https://eraorg.sharepoint.com/sites/EraTeam. Web part will be skipped (web part ID: 824b0bdc-c50d-424d-8d7e-eaebb01863cb
To back up Web Parts with the Modern App-Only Authentication method, Veeam Backup for Microsoft 365 requires setting the "Export Mode" property of the web part from "False" to "True" to make this Web Part exportable and available for backup. Sometimes changing the "Export Mode" property is prohibited by a SharePoint administrator, and thus Veeam Backup for Microsoft 365 cannot change it and back up the Web Part. When this occurs, the "Cannot change WebPart ExportMode to 'All'. WebPart will be skipped" warning is shown.