Access internal service in namespace without sidecar injection

Hey there,
I have a problem in our cluster accessing an application over a headless service in a namespace without sidecar injection from a namespace with sidecar injection. As soon I remove the sidecar injection from the service the request works. I did not now that this causes an issue at all. Is there anyone who already had that issue and can help?

pod in NS A (sidecar) → headless service in NS B (no sidecar) → pod in NS B (no sidecar)

We are running istio version 1.15.2 in a AWS EKS cluster version 1.20. Thanks for you help in advance.