Unexpected Metadata in Copilot Studio Response

In Copilot Studio, I set up a child agent to handle fallback. If the parent agent cannot provide an answer, it routes the query to the child agent. This works as expected, but the response includes the following text next to the answer:

{"explanation_of_tool_call":"The user’s query has been fully addressed with clear instructions and a supporting link, so the intent is now complete."}

I did not configure the agent to return any metadata, and I’m not sure whether this message is coming from the parent agent or the child agent.

Has anyone encountered this issue or know how to prevent this extra content from appearing in the response?