Actually I also faced the same error with Azure Blob Storage account.

This error getting from the datasource. (Error with data source: Credentials provided in the connection string are invalid or have expired.\r\nFor more information on troubleshooting connection issues to Azure Storage accounts, please see https://go.microsoft.com/fwlink/?linkid=2049388 Please adjust your data source definition in order to proceed.)

When we run AI Search Indexer with private endpoint connection in Azure Storage we need to add a managed identity (system assigned) to the datasource. Screenshot of datasource for help