Log while testing, not chat
Send debug output to the Log node so you can watch a flow work without spamming your channel.While you are building a flow, you need to see what it is doing. Sending that to chat clutters the channel and confuses viewers.
Wire a Log node in instead. It records the value where you can read it back, and it never reaches chat. Leave the logging in place while you iterate, then, once the flow behaves, swap the parts your viewers should actually see for a real Send Chat Message or Reply to Chatter.