Sending a log search alert with cross tenant target resource will no longer be supported

As of March 15, 2024, this behavior will change and sending a log search alert with a cross tenant target resource (except for the lighthouse case) will no longer be supported. Alerts will not be sent to unauthorized target resources, and log search alert rules with an unauthorized target will be ignored. This will ensure that only authorized users can receive and investigate log search alerts.
Source: Microsoft Azure – aggiornamenti