What does `* Mark bundle as not supporting multiuse` mean in my curl trace?

Solution 1:

From https://github.com/curl/curl/blob/master/lib/http.c#L3611 :

if(conn->httpversion < 20) {
   conn->bundle->multiuse = BUNDLE_NO_MULTIUSE;
   infof(data, "Mark bundle as not supporting multiuse\n");
}

It is a feature of HTTP/2. See, e.g., https://www.cloudflare.com/website-optimization/http2/what-is-http2/