This video is a walk through for using my free PowerShell script to report on any forwarding of emails from your Microsoft 365 environment. You can grab the script at - https://github.com/directorcia/Office... then use it once you have connected to Exchange Online, which you can do with other free scripts in that same repo.
Unexpected email forwarding could be a sign of business email compromise and you may wish to run this process regularly to gain better insight on what is being automatically sent outside your environment.