Use ImageEngine to optimize images through Cloudflare workers. A starting point which aligns the cache key computation on both sides

cfWorker.js

addEventListener('fetch', event => {
  if (event.request.url.match(/\.(jpe?g|png|gif|svg|webp|avif|jxl)/i) && event.request.method === "GET") {
    event.respondWith(handleRequest(event));
  }else{
    event.respondWith(fetch(event.request));
  }
})

async function handleRequest(event) {
  const request = event.request;
  const url = new URL(request.url);
  const path = url.pathname + url.search;

  //defined as environment variable
  const imageEngineURL = `https://${IMAGEENGINE_DELIVERY_ADDRESS}${path}`;

  // Compute a custom cache key based on the URL and  header

  const cacheKey = url+request.headers.get('Accept')
    +request.headers.get('Accept')
    +request.headers.get('sec-ch-width')
    +request.headers.get('sec-ch-dpr')
    +request.headers.get('sec-ch-viewport-width')
    +request.headers.get('ect')
    +request.headers.get('save-data')
    +request.headers.get('sec-ch-form-factor');
  console.log("Key "+cacheKey);

  const cache = caches.default;

  // Try to find a match for the request in the cache
  let response = await cache.match(cacheKey);
  if (!response) {
    //console.log("Cache miss for "+url);
    
    // Clone the original request to modify it for the origin fetch.
    // Adding a cache buster to the url to avoid the Cloudflare cache
    let originRequest = new Request(imageEngineURL+(url.search ? '&' : '?')+'cfbust='+new Date().getTime(),request);

    // Add the required imgeng-inputcdn custom header to the cloned request.
    originRequest.headers.set("imgeng-inputcdn", "cloudflare,1");
    originRequest.headers.set("cf", {cacheTtl: 86400,cacheKey: cacheKey,cacheEverything: false, polish: false,cacheTags: ['ImageEngine']});

    // Fetch the response from the predefined origin
    response = await fetch(originRequest);

    // Check if the response is ok to cache
    event.waitUntil(cache.put(cacheKey, response.clone()));
  }

  return response;
}