I moved this conversation to a new thread.
The cL termination basically means:
c : the client-side timeout expired while waiting for the client to
send or receive data.
L : the proxy was still transmitting LAST data to the client while the
server had already finished. This one is very rare as it can only
happen when the client dies while receiving the last packets.
If this is true - the termination code is correct and there is no bug you are hitting in haproxy, then the client closed at a very specific moment (when the response from the server was fully received but the client didn’t).
It is not completely impossible that you are hitting a bug though. You will have to correlate if there are real issues with those requests, or get a complete network capture of a request like this.