I don’t think “Did you know symptoms X and Y are signs of clinical mental illness Z?” is appreciably different from “You very possibly have mental illness Z”, which is the practical way that “You have mental illness Z” would actually be phrased in most contexts where this would be likely to come up.
Nevertheless, your first and third paragraphs seem right.
In a conversation, you get another reaction if you ask a question that indirectly implies that the other person has a mental illness than if you are direct about it.
The phrasing of information matters.
I don’t think “Did you know symptoms X and Y are signs of clinical mental illness Z?” is appreciably different from “You very possibly have mental illness Z”, which is the practical way that “You have mental illness Z” would actually be phrased in most contexts where this would be likely to come up.
Nevertheless, your first and third paragraphs seem right.
In a conversation, you get another reaction if you ask a question that indirectly implies that the other person has a mental illness than if you are direct about it. The phrasing of information matters.