Istio 1.9 Bookinfo - Incorrect response direction of ratings/details

I have a question on traffic direction in the bookinfo application. I am exploring Envoy WASM filters and have deployed a simple filter that lists the direction of requests/responses. However, I am confused about the direction of responses by the leaf nodes such as details and ratings. For example, the log shows that after a request from productpage, the response of details is classified as “inbound” in the filter according to the listener direction. This seems wrong. I would classify it as an outbound response to productpage. When I check the reviews nodes, the direction seems correct. Is there a reason why the response direction is inbound? Is it possible to change the direction of the envoy listener in Istio?
If requested, I can provide the or wasm file I have used.

The proxy log for a single request to ratings: ratings log -
In the log you can see that both onRequestHeadersInbound and onResponseHeadersInbound are traversed, but nothing outbound.
The I used for this is defined here: filter file -


Does anyone know what could cause this? Or how to configure Istio in such a way that the reply by ratings or details is classified differently.