SharePoint Online - Custom App authentication

I’m unable to backup SharePoint Online.

• Failed to validate any of the configured Azure Apps against the SharePoint Tenant Admin site. 1) Please verify the SharePoint Tenant Admin Url. 2) Please check the credentials and permissions for the configured apps. 3) Please ensure Custom App authentication is enabled on the SharePoint tenant (https://kb.commvault.com/article/63803). [Not available]

I’ve configured this many time before, but apparently it recently became impossible to enable customAppAuthentication on new tenants.

Set-SPOTenant -DisableCustomAppAuthentication $false
Set-SPOTenant : Updating DisableCustomAppAuthentication is not allowed anymore for new tenants. This is part of Azure ACS feature retirement plan as outlined in https://aka.ms/retirement/acs/support.

The customAppAuthentication is still described as a prerequisite in the Commvault documentation, even for version 11.38:

https://documentation.commvault.com/11.38/essential/complete_office_365_guided_setup_for_sharepoint_online_using_custom_configuration_option.html

Is there any alternative available ?