DLP policy to apply M365 group mailbox address

Is there a way to apply a DLP policy to M365 Group mailbox itself? Our organization uses some Group mailboxes as shared mailboxes i.e. users have been assigned 'Send As' permissions on group mailbox and send emails from group mailbox. These emails has sender address of group.

We use scoped DLP policies whereby policies are configured to apply to a mail-enabled security group. Now, we cannot add the group mailbox as a member to mail-enabled security group. Is there any way we can scope the policy to group email itself?