Route fetch and fulfill with 304 Not Modified cached

Hi, i m using the example from https://playwright.dev/docs/api/class-route#route-fetch to modify a response. The .fetch() method seems to handle this quit fine in chromium, firefox and edge, but in webkit i have the problem that in some cases the route is cached and simply responses with 304. The body is empty, therefor .json() throws. So what i did is fetching again if it returns 304:

let response = await route.fetch();
if (response.status() === 304) {
   const headers = route.request().headers();
   headers['Cache-Control'] = 'no-cache';
   response = await route.fetch({ headers });
}

But shouldnt the cache be deactivated in the first place or .fetch handle it for me?

response was cached (and remain unchanged) before i use page.route