ETag header not sent

We’re trying to set the etag header in a worker like this:

    const headers = new Headers();
    headers.set('ETag', 'test');

    return new Response('test', {            
        headers,
    });

but it doesn’t reach the client. Is there a list of approved headers that you can send from the worker?

Found this post about that only week ETags are supported by default:
https://support.cloudflare.com/hc/en-us/articles/218505467-Does-Cloudflare-support-ETag-headers-

When changing to use weak etags it works just fine from the worker.