Cloudflared not disconnecting streams after the browser/client disconnects

We're successfully using the Cloudflare Argo tunnel for most projects in our inside a Kubernetes cluster, but are running into an issue when using [Server-Sent Events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events) (basically long living plaintext stream).

At the moment when a client/browser disconnects from a SSE stream the Nginx container and the underlying PHP-FPM container aren't notified of the disconnection. When checking the Cloudflared transport log, it's actually still sending data from the stream back to Cloudflare after a client has been disconnected.

I've created a repository to demonstrate this behavior: https://github.com/niels-nijens/cloudflared-sse-test