response headers of backend url

HTTP/2 200 
access-control-allow-origin: *
cache-control: max-age=3600
content-type: text/html; charset=utf-8
etag: "4c94e079d45218460e7c0db2d010abfba3a4cff229547fcdeb2d6059333310"
last-modified: Wed, 11 Oct 2023 05:24:20 GMT
strict-transport-security: max-age=31556926
accept-ranges: bytes
date: Tue, 06 Aug 2024 16:07:20 GMT
x-served-by: cache-bom4743-BOM
x-cache: MISS
x-cache-hits: 0
x-timer: S1722960440.785547,VS0,VE269
vary: x-fh-requested-host, accept-encoding
alt-svc: h3=":443";ma=86400,h3-29=":443";ma=86400,h3-27=":443";ma=86400
content-length: 25601 

I want to proxy my requests without exposing backend URL

www.frontend.com/login?queryParams -> www.backend.com/login?queryParams

these are response headers after deploying cloudflare worker on this route

 HTTP/2 301 
date: Tue, 06 Aug 2024 16:09:59 GMT
content-length: 0
location: https://www.backend.com/login
cf-ray: 8af04b640ee63217-BOM
cf-cache-status: DYNAMIC
retry-after: 0
accept-ranges: bytes
alt-svc: h3=":443"; ma=86400
x-cache: HIT
x-cache-hits: 0
x-served-by: cache-bom4751-BOM
x-timer: S1722960600.703772,VS0,VE0
report-to: {"endpoints":[{"url":"https://a.nel.cloudflare.coms=CeseREkv7hOLD9aXW6iL8G9oYh6nSUkSyp5DnEjnw4mTXM3CTN%2F7ppgZ%2BdJYdBjwH5edvop1ztV7SWEKm6bMtBRHq5o0eKetmrvG%2Bc3x7Dtb%2FfIjA%2BJPCg%3D%3D"}],"group":"cf-nel","max_age":604800}
nel: {"success_fraction":0,"report_to":"cf-nel","max_age":604800}

see above response headers show its a permanent redirect

my wrangler.toml

```
name = "fronted-to-backend-proxy"
main = "src/index.ts"
compatibility_date = "2024-07-29"
compatibility_flags = ["nodejs_compat"]
routes = [
    { pattern = "www.frontend.com/login", zone_name = "company_domain.com"},
    { pattern = "www.frontend/refer", zone_name = "company_domain.com"},
]
```

index.ts

export default {
    async fetch(request, env, ctx): Promise<Response> {
        // Parse the incoming request URL
        const url = new URL(request.url);

        // Define the URL patterns and their corresponding proxy endpoints
        const proxyMappings: { [key: string]: string } = {
            "/login": "https://www.backend.com/login",
            "/refer": "https://www.backend.com/refer"
        };

        // Check if the URL pathname matches any of the specified patterns
        if (proxyMappings[url.pathname]) {
            // Modify the URL to point to the new endpoint
            const proxyUrl = new URL(proxyMappings[url.pathname]);

            // Append query parameters to the proxy URL
            url.searchParams.forEach((value, key) => {
                proxyUrl.searchParams.append(key, value);
            });

            // Create a new request with the modified URL, including headers and session
            const modifiedRequest = new Request(proxyUrl.toString(), {
                method: request.method,
                headers: request.headers,
                body: request.body,
                redirect: request.redirect
            });

            // Fetch the modified URL and return the response
            return fetch(modifiedRequest);
        }

        // If no match is found, return a 404 response
        return new Response("Not Found", { status: 404 });
    }
} satisfies ExportedHandler<Env>;

frontend.com is subdomain configured with cname <>
backend.com is also a subdomain configured with A record

both have flexible ssl configured in cloudflare

Any suggestion is much appreciated.