ECS services must reference an IAM role, not an IAM policy, because pointing the service Role property to a policy resource can break permission binding, make access controls harder to manage and audit, and increase the chance of privilege misconfiguration. Check AWS::ECS::Service resources’ Properties.Role. The value must be a reference to an AWS::IAM::Role (logical ID or ARN) and must not be the logical ID of an AWS::IAM::Policy resource. Attach permissions to that role using ManagedPolicyArns, an AWS::IAM::ManagedPolicy, or inline policies defined on the AWS::IAM::Role itself. ECS services whose Role property refers to an AWS::IAM::Policy logical ID will be flagged.