Question

Hello,
I came across the following question: A person asks for my opinion about someone else (for example, whether I think he is shallow, deep, has a good head on his shoulders, etc.), except that the person he is asking me about is actually me (and he does not know that he is talking about me)…
If at that point I say good things about him (which I believe are true), am I violating "misleading someone" or is there a concern of "falsehood"?
It seems to me that from the standpoint of Jewish law, no. Maybe morally it would be better to tell him.
What do you think? I would be happy for sources