Why is my chat speaking non-words like um and uh?

More details would be helpful, but chances are you have modified the system prompt on your LLM to be something like "appear less confident" or "add a sense of humility to your responses"

Ask it what its primary considerations when composing responses are.

One of the most positively reviewed behaviors was the breathing sounds for Eleven labs chats. I guess it goes with whatever is rewarded.